Music Hardware

Music001

Kendall Wrightson opens the lid on electronic music

Major electronic musical instrument manufacturers such as Yamaha, Roland and Sequential Circuits have not been slow in incorporating the latest technology into their machines. The rate at which synthesisers, sequencers and drum machines appear is almost as staggering as the facilities they offer.

Most home computers have sound facilities. The better ones, musically speaking, like the CBM-64 can produce reasonable results if you have the patience and aptitude to write your own programs.

Dedicated synths involve a lot of clever hardware as well as software and the more professional musical home computer packages either include extra hardware such as voice cards to transform the micro into a synth, or use the micro to control a dedicated synth as we shall discover.

Synthesisers utilise many techniques to create imitative sounds. The most common method, known as subtractive synthesis, involves control of the frequency of one or more oscillators from a music keyboard, guitar or computer.

The oscillators produce wave forms of complex harmonic structure, like triangle, sawtooth and square waves. These wave forms are then modified by a sort of special tone control called a filter.

Varying the filter’s cut-off frequency removes harmonics of the complex wave form – hence the term subtractive. However harmonics may also be greatly emphasised by increasing the filter’s resonance or Q.

The filtered tone then enters an amplifier, but will sound uninteresting to the human ear, because it is static. This is overcome by generating modulation signals which can be routed to the filter, the amplifier and the oscillators. These modulating signals may be generated by low frequency oscillators or LFO’s, velocity and pressure sensors fitted to the keyboard, and by performance controls.

One special kind of modifying signal is an envelope – so called because of the way it shapes sound. The envelope’s parameters, attack, decay, sustain and release – ADSR – are set up by the user. When applied to the amplifier, the envelope shapes the volume of the sound applied to its input in the following way – having played a note, the attack rate controls the time taken for the sound to reach a maximum level. Decay is the time taken for the sound to reach a sustain level. The sound will remain at this sustain level until the key is released whereupon the sound will die away at a rate dependent upon the release setting – see figure 1.

Fig001

Figure 1. ADSR envelope.

A collection of control settings is called a patch. Before the advent of the microprocessor and cheap memory, a change of patch involved twiddling all the control knobs to their appropriate positions – a somewhat time consuming activity, particularly during a live performance!

These days life is made easier because patches are stored in memory and may be instantly recalled. Modern synths also allow patches to be saved to and loaded from tape.

Other methods of synthesis include frequency modulation techniques or FM, additive synthesis and more recently, the sampling of real sounds. However, the terminology described above may be applied to any method of synthesis.

Simulating drum sounds electronically is extremely difficult. For this reason contemporary drum machines use samples of real drum sounds. The sounds are digitised through an analogue to digital converter – ADC – and stored in Eprom. So when you hit the trigger pad or press the button, the Eprom’s contents are clocked out through a digital to analogue converter, or DAC, under microprocessor control.

Real time recording on a drum machine means hitting pads or buttons to an accompanying metronome click. The data provided from this activity is then stored in memory. Thankfully, timing errors can be automatically corrected if desired.

Individual rhythm patterns are each assigned a number so that they may be chained together to form a “song”.

For those of us with no intention of hitting buttons in time with a metronome, some machines offer step time programming. In step time, a number of beats to the bar is chosen. Then decisions are made regarding which drums should sound on which beats.

A home computer could make step time programming easier by displaying information on a monitor. Software is becoming available for the Apple IIe, which links via RS-232 to the Drumulator machine, to perform this very task.

MPC Electronics went one step further by incorporating a ZX-81 as an integral part of the percussion computer. The ZX-81 is connected via an interface unit which also contains the software it runs. The addition of the Sinclair 16K RAM-pack increases the machine’s memory, while the software allows the loading and saving of patterns, as well acting as a visual aid to composing.

Sequencers, like drum machines, record data with respect to time. The difference is that sequencer data represents keyboard depressions and the length of time that keys are held down, so why not make a conventional analogue recording?

Well, first, a sequencer can play back at different tempos, without affecting pitch. Secondly, the sequence may be played back using a different pitch to the one it was programmed with. Thirdly, sequencers offer the non-musician the chance to compose music through step time note entry, where pitch and timing information is entered separately.

Again, like drum machines, sequences can be chained together to form “songs”. The sequence order can be changed if it is unsatisfactory.

Originally, synthesisers used to generate a control voltage or CV – proportional to the pitch played, and a gate signal – in proportion to the length of time a key was held down. It was these signals, after analogue to digital conversion, that sequencers used to record. This was fine for synths which were capable of playing only one note – monophonic – since it would require only four cables to connect a synth to a sequencer for record and playback.

Music002

Modern integration developments have led us to eight and 16 note polyphonic synths. The problems encountered in connecting up 32 cables from an eight-note polysynth to sequencer do not encourage musical spontaneity! The situation is further aggravated when you discover that different synths use different CV and gate voltages!

However these, and other problems have recently found a solution in the development of a data protocol for electronic musical instruments called MIDI or Musical Instrument Digital Interface.

MIDI is a new word to add to your vocabulary of computer-speak. It came about, like MSX, out of a need to standardise a very non-standard world. Things begin to get very exciting when synths, drum machines and sequencers operate together as an integrated unit. However, before MIDI was agreed by the major synth manufacturers, it was difficult to get excited about such things due to the inherent non-compatibility of products.

Each drum machine had its own way of telling the outside world it had started, then there’s the sequencer problem mentioned earlier.

MIDI cures such problems, as well as allowing the transfer of much more specific messages.

Physically, MIDI appears as two or three 5-pin 180 deg. DIN sockets on a synth, drum machine or sequencer – MIDI In, Out and Through. The MIDI Through socket outputs a direct copy of data entering the MIDI In socket. A manufacturer does not have to fit a MIDI Through facility. Only two of the five DIN pins are used, so MIDI transmits and receives data serially.

This particular facet of MIDI was heavily debated because it was felt by some manufacturers that a serial link would be too slow. In practice there have been complaints of noticeable delays when transmitting keyboard data to more than three synths at once. However, the convenience of using single 5-pin DIN leads rather than multicore cables must have tipped the balance for the supporters of serial transmission.

MIDI runs at 31.25 Kbaud asynchronous. The word format is shown in figure 2. So, to MIDI-fy your micro, wire up an asynchronous communications interface adaptor or ACIA, like the Motorola 6850 to the expansion orifice of your micro. Address the ACIA nicely and tell it to transmit and receive as in figure 2, i.e., one stop bit, one start bit and no parity.

Fig002

Figure 2. MIDI serial

Wire the ACIA transmit output and input to appropriate 5-pin DIN sockets.

Don’t forget to opto-isolate the MIDI In input otherwise nasty earth loops could develop. Now write some brilliant software and make lots of money! Seriously though, for anyone considering designing their own interface, the MIDI hard and software specification is available from the MIDI Users Group, 8426 Vine Valley D.R. Sun Valley, CA91352, U.S.A.

The MIDI data format is divided into two categories – channel commands and system commands. The channel command format allows for 16 unique channels for communication between instruments.

One of the most fundamental tasks MIDI must allow is for one synthesiser to play another. The channel command structure gives three ways or modes of performing this task.

In omni mode, all synthesisers connected together will transmit and receive on all channels. In poly mode each synth is set by the user to receive on only one channel. The synth will therefore ignore any incoming data which is not on its assigned channel. Figure 3 shows a typical poly mode set up. Note that Synth A. is used as the MIDI transmitter!

Fig003

Figure 3.

Mono, the third possible mode, allows the allocation of different MIDI channels to individual voices within one synth. This opens up the exciting opportunity of one synth playing different patches on each voice. However, at the time of writing, the only reasonably priced synth capable of mono mode operation is the Sixtracks made by Sequential Circuits.

Let’s take a meaningful example – suppose a middle C is played on a synth. In the MIDI scheme of things this is called a note on event. Three bytes will be transmitted from the synth’s MIDI Out socket to represent this:

First Byte – 1001 nnnn

Where 1001 means note on event and nnnn is the MIDI channel number (0 to 15)

Second Byte – 0kkk kkkk

Where kkk kkkk is the key number – 0 to 127 semitones

Third Byte – 0vvv vvvv

Where vvv vvvv is the velocity at which the note was played (0-127 levels). So, if you delicately stroked the key, you would generate a velocity byte equal to 1. If, however, you hit the key with a large mallet, you would generate a velocity of 127 – this practise is not advised.

Synths which do not have velocity sensitive keyboards transmit a velocity byte of 64 (decimal) as a de-fault value. So, if a middle C was played on a non-velocity sensitive synth set to MIDI channel 1, the data transmitted would be:

144,60,64. (decimal)
90,3C,40. (hex)
10010000, 00111100, 01000000 (Binary)

Other channel commands include note off event – 3 bytes – and patch change request – 2 bytes.

The second category of commands, systems commands, is divided into three types: system common; system exclusive and system real time.

System common commands are those intended for all devices in the system. An example is asking synths to tune their oscillators, a tune request – 1 byte.

System exclusive commands are those applicable between instruments of the same internal design. The system exclusive command, 240 (decimal) is therefore followed by a number representing the manufacturer – Sequential Circuits’ number is 01.

The number of bytes which follow is dependent on the nature of the data to be transmitted. An end of system exclusive is flagged by transmitting 247. Examples of system exclusive information are patch dumps and specific control knob changes.

The third category of system commands, system real time, are those messages concerned with synchronisation. They can be transmitted at any time by sequencers or drum machines. Examples are, Start, Stop, Reset and Timing Clock. The timing clock pulses are sent at a rate of 24 clocks per quarter note. Most MIDI drum machines and sequencers have Trigger, Clock or Sync outputs like their non-MIDI counterparts so as not to alienate customers with pre-MIDI equipment.

A micro fitted with suitable MIDI interface could perform wondrous tasks as part of a MIDI set up. Here are some examples:

  • Sequencer
  • Patch data dump to take on disc.
  • Patch data display.
  • Music transcription.
  • Intelligent arpeggioator.
  • Educational software.

The following is a survey of commercially available interfaces and software for home micros. The list is not exhaustive, the criteria being to cover as many micros as possible.

CBM 64

Sequential Circuity, the pioneer of MIDI, has taken the CBM-64 under their wing and come up with a 400C note real time sequencer called the Model 64.

The Model 64 allows overdubbing, auto time correction and transposition. Its six tracks can be chained together and both sequences and songs may be dumped to tape or disc. A drum machine sync input is provided, although sequences may be recorded without a drum machine connected.

Passport Designs – designer of the Soundchaser software – will shortly be launching a MIDI card for the CBM-64. The card includes MIDI In, Out and drum sync connections. The MIDI/4 software provides 16 real time tracks, each of which can be assigned its own MIDI channel and instrument name.

Apple

The MIDI/4 software can also run on an Apple II or IIe using Passport’s Apple interface card. This card is also used for music transcription software called Polywriter. The software is a four note polyphonic version of the Notewriter monophonic transcriber for the Soundchaser system. Polywriter allows printouts in eight different formats, ranging from single, treble and bass clef parts, to large orchestral stores.

Spectrum

The ZX Spectrum is popular among the small entrepreneurs, like Upstream whose software consists of a six track, 3500 note real/step time sequencer. The interface, which is included in the overall price of £179, boasts a trigger output along with MIDI In, Out and Through connections. Optional extras include editing facilities and a dot and stave graphics display.

XRI Systems is asking £108 for its MicronMidi interface and software for the Spectrum. Micron is an 8,000 note real time sequencer with MIDI In, Out and Through connections as well as a trigger output. The Micron can also handle step time note entry in eight tracks, each of which can hold 3,000 notes. Tracks may then be merged or “bounced’’ onto on track to make space available for further recording.

Yamaha CX5

If you are considering changing your micro, then Yamaha’s MSX computer, the CX5 may well be worth the wait, it is expected in November.

The CX5 is actually going to be marketed as a musical instrument as well as a home computer in this country, due to the fact that it comes fitted with MIDI interface and an FM voice module as standard.

The Yamaha CX5 is not the same as the Yamaha Y1S503 MSX computer reviewed by the British computer press recently.

Having typed Call Music, the CX5 becomes an eight note polytechnic, 48 patch synth. There is also a rhythm box which unfortunately is rather weak.

The CX5 also allows 48 of your own FM synth patches which are used in the CX5’s built-in real time sequencer. The CX5 is expected to retail for about £560, fair dos for its synth facilities alone.

BBC

The BBC Model B gets the MIDI treatment from Electro-Music Research (EMR). Its Miditrack software is step time only onto six tracks, however dynamics can be programmed. The Interface which connects to the Beeb’s 1MHz Bus, provides MIDI In, Out and drum machine synchronisation facilities. The interface and software is expected to go for about £120.

Conclusions

  • MIDI, though still very young, has definitely caught the imagination of both manufacturers and public. Its now almost impossible to sell any electronic musical instrument that doesn’t feature MIDI in its specification.
  • Both the Soundchaser and PDSG systems are likely to incorporate MIDI shortly.
  • At present, the cheapest polyphonic synthesiser with MIDI is about £650; the cheapest MIDI drum machine is £950. So, assuming you use a MIDI home micro as the sequencer, a professional set up is going to cost about £1,750. However, the prices of synths and drum machines has been falling sharply over the past five years and this is a trend that is sure to continue.
  • It’s clear that there are plenty of ways of getting extremely musical with your micro, even if your micro has not expressed a musical bent in the past. Why not take the plunge? It could prove to be a very rewarding experience.

Casio – ZX Spectrum

Casio has been producing electronic keyboards by the million in the last few years. Indeed a recent survey asking young people to list their favourite toys, had portable keyboards up at the top of the list along with micros and BMX bikes.

It is good to know that you can now link a Casio MT-200 portable keyboard to a ZX Spectrum – and most other popular micros – via the Casio PA1 interface. The software, listed in the MT-200 manual turns the Spectrum into a sequencer with editing facilities.

Alternatively the software is available on cassette from Micro Musical Limited, which is also working on a system called Microlink 2. This will allow the linking of two existing Casio models – the MT800 and PT-80 – to the Spectrum to provide a sequencer which can also turn the Casio auto-rhythms on and off.

Soundchaser for the Apple

The Soundchaser turns an Apple II or IIe micro into a dedicated synth, through the insertion of three cards into the Apple’s magic slots. Also provided is a four octave music keyboard.

Passport Design’s Four Track Performance Software makes the Apple act like an eight voice polyphonic synth. There are two soft oscillators per voice, each with independent ADSR’s and one LFO which can independently frequency modulate either oscillator.

Because the oscillators are soft, you can edit existing waveforms or waves on the VDU, using a joystick or create your own. You can also build up a wave by controlling the amplitudes of a table of 16 harmonics. This is additive synthesis mentioned earlier.

All waves displayed may be printed, as can voice parameters.

The Soundchaser also provides a filter, and although you cannot control it dynamically with the ADSR envelopes, it’s possible to type in the cut off frequency then see as well as hear the result. It is this combination of both additive and subtractive synthesis which makes the Soundchaser produce such a wide variety of sounds.

Also included in the software is a fourtrack real time polyphonic sequencer, although step time editing software is available. The sequencer allows four different patches to play up to eight notes simultaneously. All voice and sequencer information can be stored on disc as wave or track files.

The Hardware and Four Track Performance Software comes to £1,369, which may seem a lot, but comparable dedicated systems cost between £3,000 and £8,000.

PDSG for the BBC

A similar system to the Soundchaser is being developed for the BBC Micro by Clef Products. The Programmable Digital Sound Generator or PDSG, allows 8-32 note polyphony from a five-octave music keyboard which is included in the provisional retail price of £400. Software being developed includes waveform creation and sequencing. It will be interesting to see how the PDSG compares to the Soundchaser when it is formally launched.

First published in Your Computer magazine, September 1984.

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Psion Organiser

Psion_001

Kathleen Peel tests the pocket computer that fills the same space as £100.

Psion the software company that produces much of the Sinclair Spectrum official software and the bundled software – Quill, Archive, Abacus and Easel – for the new Sinclair QL, has branched out into the computer hardware business, an area that has seen many recent failings by both large and small companies.

The excursion into the apparently risky hardware manufacturing side of the business comes about by the desire to produce what Psion describe as a new type of computer product called the Psion Organiser.

The Psion Organiser is a calculator-sized pocket computer featuring a 16-character LCD display, a 36-key keyboard and an 8K plug-in Eprom memory pack or datapak. The calculator-type keys are protected while in the pocket by a sliding cover which, when withdrawn, exposes the plug-in memory underneath the keyboard and the display contrast adjuster control on the right-hand side of the display. Complete withdrawal of the cover gives access to the PP3 9 volt battery compartment.

Psion_002

The computer is based on the Hitachi 6301X CMOS 8-bit processor, which contains 4K of on-chip ROM. This is supported by 2K of RAM for the calculator working registers, system variables and an 8K Eprom for program and/or data storage.

For £100 the user gets a bare bones calculator with a 16-character alpha-numeric LCD display – no scientific functions with parenthesis limited to a depth of two – and a built in database facility, capable of searching the 10K of character storage – 8K Eprom – for a specific number or character string within five seconds.

The Organiser is activated by using the On/Clear key and powers up with the display showing the time, date and month. The time may readily be adjusted as indeed it needed to be. The machine provided for review stopped the real-time clock from running when the machine was switched off, the replacement machine had no such problems.

The Mode key selects the current operating mode, that is:

  • Enter for general purpose free format database entries and editing.
  • Call for performing calculations.
  • Off which the user Executes to switch off.

Each individual process is performed by use of the Execute key – calculations are entered in the normal manner and the Execute key pressed instead of the more usual calculator = or Enter key.

Data is simply typed while in the Enter mode using the alphanumeric keyboard, each file being saved using the Save key with the display indicating whether the data is saved in datapak 1, or 2 if two datapaks are installed, according to the user’s choice.

The database needs to be fairly static, data changes simply overwrite the existing data in memory to make it unreadable and the new file is written into a clean area of memory. Fast changing databases will become extremely wasteful of memory.

The database in each datapak must be consistent; the user can store telephone numbers, train timetables and appointments together within one datapak but there is no way of restricting a search to a specific segment or groups of files in an individual datapak.

Find2 string$ will find every occurrence of string$ within all the databases in datapak 2. Therefore as an electronic notepad, the user is required to keep with the Organiser all the necessary databases separately which could become expensive in terms of datapak cost, and add considerably to the amount the user has to carry around.

The 8K Eprom can store about 200 names, addresses and telephone numbers. A search may be conducted using the Findn string$ function, every record containing string$ will be displayed, otherwise the computer keeps searching for a match. If there is no match, the message “not found” is displayed. If a string$ is not given for the search, the computer will step through every file within the database.

By adding a program pack – £30 Finance, Mathematics or Science Paks are available – the Organiser is provided with further modes of operation:

  • Copy for copying between datapaks.
  • Cat used to access programs.

The Organiser is also capable of performing the same trigonometrical and scientific functions as found in the more comprehensive calculators.

And lastly a procedural language POPL is added. Each procedure is limited to a length of 200 characters, with an individual line not exceeding 100 characters. POPL supports 26 variables and can pass parameters between procedures – there is Goto a label and looping facilities.

Under normal conditions, rewriting code is not a problem as the program storage media is reusable. With the Eproms it is not and once written to, that space cannot be re-used until the datapak is re-formatted which clears the whole of the datapak ready for a fresh start.

The Organiser may be expanded to incorporate two 16K Eprom datapaks, these cost £20 each but increases the in memory storage capacity up to 40,000 characters. The user may install 8K Eprom datapaks which cost £13, but either way strikes me as being pretty expensive for storing data.

The datapaks may be reused up to 100 times by reformatting – wiping clean all of the Eprom; remember you cannot selectively erase. This will cost £3.50 if done by your local stockist or the large user may purchase a Formatter for £45 which can reformat two datapaks in 30 minutes.

The manual supplied is 1/4 A4 size of about 50 pages of text and diagrams. Most details are explained twice but for those who so far have shown no interest in computing, the documentation will be difficult to understand. The average computer user will find no problems other than the programming requirement of learning yet another language, POPL, which can hardly be of use in any other context.

The RS-232 expansion unit, which costs £25, permits the user with a modem to downline load data via a telephone line to a remote computer. Computer to computer data transfer is also possible.

Conclusions

  • Although very simple to operate as a database with a single integrated data file, the Organiser cannot handle separate databases residing on the same datapak.
  • The database being searched needs to be fairly static, if it is going to change daily as a stores inventory might do, then the necessary changes to the database are going to use up the available memory space extremely quickly.
  • Program development is likely to suffer the same fate. It is not possible for a user to write and enter a program without faults, and the Organiser will allow the user to work on only one procedure in RAM at any one time.
  • The Organiser is going to be very expensive to run as a computer. The development of software which is
    always subject to change and revision does not lend itself to the type of storage media employed in this computer design.
  • The use of Eproms as the storage media imposes restraints on the programmer, a requirement for a local Eprom formatting service and fairly substantial power requirements on the hardware designer.
  • The Organiser appears to fit those types of market where data security is essential and, of course, using
    Eproms gives a very high level of security, but logistically I’m not sure. The data typed in is secure, but whether it can be entered correctly using the calculator-type keyboard and very small screen display without a lot of careful checking at the time of data entry, which the average person is unlikely to perform, is doubtful.

First published in Your Computer magazine, September 1984

Review – Tatung Einstein

Einstein

Single 3in. disc, 64K, colour and sound: Bill Bennett meets Einstein and talks relativity.

You would never guess it from the name, but the Tatung Einstein is a British micro. Made by a Taiwanese company based in Shropshire and named after a German, Jewish, American scientist, the Einstein is the usual electronic cocktail of exotic components from around the world. Disc drives from Japan, Basic from Torquay and chips from all over the shop.

I opened the box with some apprehension. Here was a mid-priced, mid-range computer complete with a disc-drive. The last time I looked at a cheap system with integral discs I had to spend three days soldering wires before it would work. The Einstein presented absolutely no problems. I timed myself and it took me less than two minutes to unpack the micro, plug it in, connect it to my TV and get a picture.

It took slightly longer to retune the TV to optimise the display but, before three minutes were up, I had managed to insert the system disc that comes with the machine, and load the directory. A number of things helped. For a start the plug was already connected. Many micros come without plugs so you have to hunt around for one to “borrow” for the computer. But, most of all, the integral disc saves worrying about cables, interfacing and the like.

Albert Einstein would never have won a beauty competition and neither would his computer namesake. However, the design of the machine is elegantly utilitarian. It is moulded out of a fairly tough-gauge plastic so you can comfortably sit a monitor or TV on top. I would not recommend this though as you would have to sit much nearer to the screen than is good for you.

Above the keyboard are two LEDs that do little more than tell you that the computer is working and what mode the keyboard is in. Next to this is the disc unit. It accepts the little 3 in. Hitachi-style microfloppies which are posted into the slot like letters into a pillar box. A button below the slot unposts the discs for you when you need to swap them.

There is a space on the right-hand side of the machine to add an extra disc unit. This would be almost essential if you were using the Tatung as a workaday business computer but a bit excessive for the home user. Between the disc and the potential disc is a grill which I thought was probably there to help aircool the insides. It turned out to be a loudspeaker, loud being the operative word.

I thought that the Oric was a touch strident with its built-in speaker but the Einstein is positively in the Motorhead class. In front of this is the keyboard. Topped by a row of seven function keys, the keyboard contains no surprises. I don’t like to see the graphics characters printed on the front of the keys, it looks messy, and most people only use them occasionally anyway. However, it does seem to be de rigueur in micro circles. I doubt if anyone will miss the Tab key, which the Einstein doesn’t have.

Along the rear of the micro are a number of interfaces. If you are going to make use of them I would suggest that you find a permanent home for the micro. They are not the sort of things that take kindly to being constantly plugged in and unplugged. There is, of course, a printer port, an interface for more disc units, up to a total of four drives and a user input output port. Just what you need to run a power
station or a cruise missile launcher.

Right in the middle of all these ports is something called the Tatung “pipe”. It sounds like a copy of the Acorn “tube”, but is much nearer in concept to the port on the back of the humble Spectrum. Like Sinclair’s port, the pipe is not much more than a simple extension lines from the Z-80.

Down the tight-hand side of the machine are two more ports. Ostensibly these are for joysticks, but are actually analogue to digital converters. If the Tatung Einstein has one obvious application, it is in the science laboratory. With all these ports around the machine it would be excellent for the control and monitoring of experiments. It is a pity the micro is named after a theoretical scientist, when it has so many practical features.

Next to the analogue ports is the almost obligatory RS232 port, though it uses a DIN socket so you will have to worry about soldering your own cables to make use of it. And, best of all, a volume control knob. Until I found this, I actually had a neighbour come round and complain about the noise.

Nobody will be surprised to discover the TV output on the right-hand side of the micro’s case, but I was disappointed to find that there is no monitor output. A computer with as many user ports as the Tatung Einstein could do with a simple RGB output as well. There is a special Tatung colour monitor to go with the Einstein, costing £240, but because there is no RGB output you cannot easily use any other manufacturer’s monitor.

The Einstein is a “soft machine”, that is its resident language and operating system are not actually resident at all. They come on disc and are loaded into the machine in a ritual the user must perform each time he or she uses the micro. Yet there is an 8K ROM which includes the machine-code monitor system. This makes the Einstein an attractive micro for the enthusiast but hardly ideal for the beginner.

Should you want to develop machine-code software, you could do so without ever entering the disc operating system. But most people will want to use Basic at some time and it has to be loaded from disc. To do this you must first load the disc operating system or DOS.

XtalDos is the operating system used by the Einstein. Because it comes supplied on disc, there is no reason why you couldn’t use another operating system. No others are available at the moment, but should XtalDos mark II appear, or should some enterprising programmer devise a version of CP/M for the micro, you will only have to pay for that disc.

XtalDos is remarkably similar to CP/M, so much so that I managed to get started knowing only CP/M and not XtalDos. But XtalDos – pronounced crystaldos – is not CP/M and will not run all CP/M software. This is a bit naughty because on the computer’s box is the boast: “Ability to run CP/M software”. There are more than 5,000 CP/M software packages available so you could be forgiven for thinking that buying an Einstein gives you access to a huge back catalogue of programs.

The Einstein does have the ability to run some CP/M software, it is just that you cannot buy genuine CP/M for it yet. What is more, it will not be cheap when it is available – CP/M system discs generally cost around the £50 mark. Further to this is the fact that, as yet, there is no CP/M standard for 3 in. discs. This means that even if there was a true implementation of CP/M for the Einstein, you would not be able to stroll down to your neighbourhood store and buy a software package off the shelf with any confidence that it will run on your micro.

I hope that someone does implement CP/M just as soon as the 3 in. standard is decided because, quite frankly, XtalDos is a minority operating system. There will never be enough XtalDos systems in circulation to justify a large software base.

There is one other possibility. The Einstein is physically able to run MSXDos. The micro has most of the right hardware and it would be a logical direction for Tatung to move in.

Despite my severe reservations about minority operating systems, XtalDos is jolly neat. So is Xtal Basic, the native language of the Einstein. It has met with a degree of acclaim from programmers but is not a good language for beginners. I found that it contained a lot of commands that could be found elsewhere but are not standard.

Xtal Basic may be better than other Basics but there will be precious few games listings published in it and there will be hardly any good books about it. But, again, because Xtal Basic comes on disc and not ROM, it is an option. There is no reason why standard Microsoft Basic could not be implemented on the Einstein or, for that matter, Forth, Pascal, Prolog or Logo. Any versions of these languages developed for CP/M could be adapted fairly easily, though it might not be an economic proposal.

The system disc comes with a few example programs which don’t show the Einstein off to its best advantage. I realise that Tatung must have bent over backwards to trim the costs to achieve the sub-£500 price tag, yet it would have been so much better if the supplied software was more imaginative. The Othello game was easy to beat and the snakes game downright boring.

I may be asking a lot but for this price I would like to have a second disc containing a word processor and a spreadsheet. This way you would be able to buy a complete system, ready to work on and for a good price.

Xtal Basic is not new, I remember seeing a version ages ago on the Sharp MZ-80K. It has a lot more commands than common or garden Basic, complete with things like Deek and Doke which are two-byte versions of Peek and Poke, strictly for the enthusiast. However, Xtal Basic is very good at handling the sound and graphics of the Einstein.

Sound is often the Cinderella feature on a computer, so my heart naturally warms to Tatung’s serious treatment of it. The Basic commands and the sheer volume and the flexibility of the hardware are all plus point for Tatung. Unfortunately, the other half of the sound and vision equation is not so good.

For a start, the colours are dingy. The red is more like a washed out pinky orange than the colour of the people’s flag and the blue just isn’t true blue at all, but a weedy purple tint.

The Basic commands controlling graphics are extensive and flexible enough and 32 sprites should keep most zappers in aliens for days. Apparently, the Einstein uses the same video chip as MSX machines. If that is the case then the Japanese invasion will be nothing to fear because the high resolution isn’t all that high, the colour not very colourful and the sprites none too spritely.

Maximum resolution on the screen gives 192 by 256 pixels – hardly high resolution for a £500 micro. There are 16 colours but, because they are so dull, it is difficult to tell some of them apart. Although they are easy to control from Basic it isn’t enough for 1984’s model.

While the graphics might be a little disappointing from the point of view of the games player, they are not all that useful for the business user either. You can select either 40 or 32 columns across the width of the screen, but both sets of characters do not look as attractive as those to be found on other micros. More importantly, I found my eyes were feeling the strain after about an hour’s use. So word processing – which anyway should really have 80 columns – on the Einstein might not be a serious proposition.

The colour resolution of the Einstein is only to the nearest character position. That is colours are defined on a 32 by 24 or 40 by 24 grid. This is about the same as on the Spectrum – hardly impressive. Drawing a diagonal line results in the chunkiest graphics you have ever seen because the lit pixels fill the whole of their row within a character space.

The manuals don’t help much either. They are so unbelievably boring that I thought they must have been written by Jeffrey Archer.

The “DOSMOS” booklet, now there’s a name to conjure with, is much more useful than the introduction book yet every bit as dull. It contains information about the machine-code monitor and how to use the disc operating system. A third book is supplied with the machine called the Basic Reference Manual. It is the programmer’s bible, yet suffers from the same shortcomings as the other two books; it is dull, contains no index, and no sensible appendices. It should at least contain a section full of memory map diagrams, screen address diagrams and the like.

I was impressed by the inclusion of a quick reference card, similar to that sent out with the Dragon 32. However, it turned out to be not as useful as I expected with no adequate description of the Basic keywords. This would be especially useful as certain Xtal Basic keywords are slightly exotic.

Although I have reservations about this micro, it does compare favourably with other systems in the same price range. The machine sits uncomfortably between computers like the BBC Micro, which is definitely a home computer with business possibilities, and the £700 ACT F1 which is a business computer with home possibilities. You can now buy a BBC for around £350 or less. It has better graphics than the Einstein, similar sound, better Basic and better manuals. But it doesn’t have discs, nor does it have as much memory as the Einstein which comes with a full 64K plus 16K of video RAM. In practice this means a 64K memory, because the video RAM lies parallel to the main RAM.

Although the BBC has a wide user base and all the advantages that brings, add-ons are expensive. The Einstein will be able to use standard add-ons thus reducing costs considerably. If you want compatibility with educational users the BBC would be a better buy, but hackers might choose the disc-based system.

Compared with the Sinclair QL, the Einstein is not very racy, but its 3 in. discs are a sight more standard than Sinclair’s Microdrives. They are also more useful, more likely to last and can hold more – 190K per side as opposed to 100K per cartridge. If you want to play games the QL will be a better bet but for serious use the Tatung should win.

Conclusions

  • The Einstein does not fit into the current spectrum of available micros very well being neither a good enough games machine nor a powerful enough business system. The cop-out answer is that it is an educational computer but that is one role it is particularly unsuited to fill.
  • Anyone purchasing the Einstein may have to reconcile themselves to owning a ghetto machine. I cannot see the dedicated software base ever getting large enough to be anything else. And as for CP/M compatibility, someone is going to have to copy each package across into the Einstein disc format and, in many cases, rewrite the software for the 40- or 32-column screen.
  • In my opinion there is a serious design fault. Had the disc drive been a standard 5.25 unit, then users would have immediate access to all the available CP/M software. I realise that this would have added to the cost but it would also add greatly to the utility of the machine.
  • There is one other problem that will be familiar to owners of the Sharp micros which have a lot in common with the Einstein, thanks to versions of Basic not stored in ROM. Should Tatung ever be tempted to make changes to Xtal Basic – the installed version is 1.11 – then software may no longer be transferable between machines.
  • All these reservations aside, the Einstein is a very low-cost way of buying a disc-based system. It is built from reliable tested technology and is unlikely to have the teething troubles of the QL. It is especially suited for control purposes and will thrill the hacker with its Xtal Basic and extensive machine-code monitor.

First published in Your Computer magazine, September 1984.

Toshiba HX-10 Review

ToshibaHX10_001

Graham Bland looks at what the vanguard of the MSX invasion has to offer.

In a bid to repeat their success in Japan, a number of manufacturers recently announced their intention to launch MSX systems in the U.K. Toshiba has emerged as the pace setter in the race to customise a micro for the more sophisticated British market. The HX-10 Home Computer seems likely to beat Sanyo’s Wavy 10 and Sony’s Hit-Bit to a place on the MSX shelves this month, albeit by a narrow margin.

Toshiba’s machine is unexciting when, compared with other systems from the land of the rising sun. The HX-10 does not have any of the goodies promised with some other MSX micros such as video interfacing, robot arms, and music synthesisers. But what it will have is a more competitive price tag.

Cosmetically, the HX-10 appears functional rather than glamorous – a slab-like dark-brown box, not exactly ugly, but it is hardly inspiring either. The overall construction is very workmanlike, a solid heavy micro that looks as if it could take a good bashing and has the endearing habit of staying put while you are typing.

Interfacing made easy

Communication with the outside world is relatively simple. At the back of the machine are phono socket connections for output to TV set or monitor, and a DIN socket to hook up a cassette recorder. Also hidden round the back is the bus connector which is ominously marked “For Only Toshiba Use”. This expansion bus connector will come into use when disc interfaces become available, as well as RS-232 drivers and the like. On the side of the machine are two D-type joystick sockets and a Centronics printer socket.

The all-important cartridge slot is accessed from above. How often this slot is used will depend on how many U.K. software houses opt for cartridge media in favour of cheaper and more popular cassettes.

As keyboards go, the HX-10’s is a long way ahead of those found on the Sord M-5 and the Spectrum, but not quite in the league of the BBC model B or Electron. As such, it represents a reasonable compromise between low-cost and usability. Of the 73 keys, five are programmable function keys – or soft keys as they are sometimes known.

A rich set of foreign characters are available from the keyboard using the Code key, including French, Spanish and Greek, as well as graphics characters which are produced using the bright-green Graph key. The minor points which annoyed me while using the HX-10’s keyboard were the tiny backspace key, the cramped cursor keys and the absurd colour scheme adopted, green, blue, brown and white.

In Japan, Toshiba was one of the few companies to offer a 64K machine. Seemingly, Tokyo’s man-on-the-street is quite happy with a measly 16K computer. Of the two systems that Toshiba had available in Japan, they wisely adapted the 64K version instead of the 32K model.

If the promise of 64K seems mouth-watering, prepare for a sudden loss of appetite when you switch on the HX-10. After the copyright message you are informed that there is only about 28K available to MSX-Basic programs. Graphics support immediately claims 16K and the rest of the missing memory is squirrelled away for some undisclosed purpose – perhaps lying dormant awaiting the arrival of a disc operating system.

Displayed at the bottom of the screen are the values of the first five function keys. The second five values may be displayed simply by holding down the Shift key. To remove this display, the command Key Off will do the trick. You can assign your own character strings to any of the function keys. For example:

KEY 1,“? FRE(0)” + CHR (13)

will print out the amount of free memory every time function key number 1 is pressed.

MSX-Basic is very nearly an 8-bit IBM PC Basic, offering a nice spread of arithmetic functions, good graphics and sound and a few other elegant touches which must make it one of the best home micro Basics around.

All arithmetic is calculated to double precision – up to 14 decimal places – which does tend to slow programs down a bit, but this trade-off is acceptable if accuracy is the most important consideration. Data types can be declared as binary, hexadecimal and octal as well as the standard characters, integers etc.

Entering programs displays both a weakness and strength in the Basic. Unfortunately, the interpreter does not check lines as they are entered. To compensate, there is an excellent full-screen editor. It is a shame that the designers could not combine both these features in the way Atari has on the 800XL.

As mentioned earlier, the HX-10’s character set is fairly complete. There is a full range of scientific symbols, a music note, signs for integration and differentiation and so forth. These characters, plus the foreign ones, point to the possible educational uses that MSX systems might have.

Program output can be formatted using the Print Using statement. This is a fairly flexible and powerful statement which is particularly useful for making numeric output look nice. If, for example, the results of a tax calculation are to be displayed to two decimal places, the following statement will ensure a uniform output:

10 PRINT USING “# # # .# # ”,TAX

Other options allow field fillers, + or – signs, and the insertion of a string variable into a constant string.

Powerful sound chip

The sound available from MSX Basic is also quite impressive. At the heart of every MSX micro lies a dedicated sound chip – General Instruments AY-3-8910 – the same chip used by the Oric Atmos and Memotech MTX series, in fact. It is capable of producing three notes simultaneously over a range of eight octaves with an optional noise channel to produce helicopter and explosion noises. To kick this chip into life, you can use one of two Basic commands: Sound or Play.

Sound is the most flexible of the two but much harder to use. It is little more than a specialised Poke instruction; values are sent to one of the sound chips’ 13 registers accessible from the Basic. Not having a manual available you will have to study the sound chip quite fully.

The Play command is much more straightforward. You are restricted to musical notes in this case, with instructions being given to the sound chip via the Music Macro Language. Music is set out in a character string, with letters like C, F and G# corresponding to the same notes as musical notation.

Note length, octave, tempo and other features will, with practice, allow most tunes to be played. All music played using this command is placed in a music queue for summary execution. So once told what it is to play, the HX-10 can continue to perform some other task. There are no equivalents of the Oric’s Zap and other sound commands.

With 16K of your precious memory dedicated to graphics support, you get the feeling that the graphics capabilities of this machine ought to be quite good. Though not in possession of an ultra-high resolution screen like the Beeb’s, the HX-10 can squeeze quite a lot from its fairly moderate 256 by 192 resolution screen. The nicest thing about MSX Basic’s graphics statements is that they are very easy to use, and due to the allocated video RAM, reasonably quick too. I can only hope that this feature is well documented.

There are commands to draw circles, lines and boxes, a Paint command, and 16 colours available. Best of all, you can declare up to 32 sprites. Fortunately, there are no Poke instructions required to set up a sprite thanks to the provision of a special variable called Sprite$. Sprites are placed on the screen using the Put Sprite command. A number of these graphics statements such as PSet, Circle, and Put Sprite have the option to specify absolute or relative co-ordinates.

By putting the word Step in front of a set of co-ordinates, the shape or point is placed relative to the last point addressed on the graphics screen. This speeds up the movement of sprites etc. across the screen as there is no need to waste time calculating the object’s next position.

Text and graphics

There is, however, no easy way to put text into a graphics screen. What you have to do is: open the graphics screen as a named file (GRP:) and use a Print# statement to send a character string to the screen. This is hardly convenient particularly as the character string will be placed at the last point addressed on the screen.

Possibly the best feature of this Basic is its interrupt statements. Rather than polling for an event such as the spacebar being pressed, you can set an interrupt which will cause a branch to a subroutine when the event occurs. The following short program will print out the product of 100 by 100 repeatedly until the spacebar is pressed, when it will print out

“HELLO”: 10 strig(0) on
20 on strig gosub 40
30 print 100 * 100 : goto 30
40 print “HELLO” : return

Interrupts may be set up to monitor the function keys, sprite collision, time intervals, and trap events such as errors and the production of a Ctrl-Stop signal. This feature of the language makes up for the omission of a While-Wend statement.

Conclusions

  • Overall, the Toshiba HX-10 is a pleasurable system to use. It does have its drawbacks but these are generally too few to worry about. It is much better than the ill-fated Spectravideo – almost an MSX computer but not quite – being curiously faster with the obvious advantage of a full-pitch keyboard.
  • It will be a long time before the full impact of MSX is realised in the U.K. The standard promises cheaper and plentiful software, lower-cost systems and peripherals, every micro owner’s dream in fact. It will probably be next year at the earliest before software houses have the courage to reduce MSX software prices, depending, of course, on whether MSX takes off in the U.K.
  • Judging by the Toshiba MSX system, the decision to purchase one manufacturer’s system against another may well rest on a single factor – price.

First published in Your Computer magazine, September 1984

Commodore 64

C64_Main_001

The 64’s strong selling point is its memory capacity, but – as Simon Beesley discovers – its other features all conspire to make it something of a force to be reckoned with.

The Vic-20’s stock has fallen slightly since it first went on sale last autumn. At the time it was welcomed as the only computer under £200 with colour and sound. Now it seems overshadowed by a number of competitors which offer more features at an equivalent price.

People tend to point to the Vic’s limited memory capacity – only 3.5K – or its constricted screen layout of 22 columns by 23 rows, and belittle its strong characteristics as secondary features. But such secondary features as well-spaced and robust keys, or a good screen editor assume great importance for anyone who spends much time programming.

Improved screen size

The Commodore 64 remedies most of the Vic’s shortcomings, while maintaining its virtues. The keyboard layout is the same and, apart from its beige colour, the casing has the same size and appearance. An extra games socket supplements the number of ports available on the Vic. These allow attachments to cassette, disc drive, program and games cartridges. A user port which will take a Z-80 cartridge to give the 64 access to CP/M software is also included. The VicModem, RS-232 and IEEE interface cartridges can also be plugged in.

Memory capacity and screen size are two areas in which the Commodore 64 improves on the Vic. 64K RAM is on board, of which 38K is available for Basic programs. The screen format gives 25 rows of 40 characters. Like the Vic, there is a choice of 16 colours and two character sets which include predefined graphic characters.

Commodore micros score highly for the ease with which one can change character sets, select graphic characters and alter the text or graphic colour. All this can be done through a combination of control and colour or graphic keys. Compare this with the laborious business of keying in a VDU command on the BBC Micro to change colour.

Easy to set up displays

Setting the background and border colours is equally convenient and just requires Poking a value into a single memory location. Multicolour mode on the Vic and the 64 enables you to use four colours within a single character space but is really only suitable for user-defined characters. Extended Colour Mode on the 64 is a new and more useful feature, which allows you to choose one of four colours for the background to a single character. The drawback is that only the first 64 characters can be used in this mode.

The 64 runs the same Basic as the Vic, itself more or less the same as Pet Basic. Programs should be transferable from other machines with 40-column displays if Peek and Poke addresses are changed.

The attractive feature of this Basic is the convenient way that cursor and colour control characters can be entered into character strings in a Print statement. They determine the screen position and also the colour of the text or graphics that follow after – making the task of setting up the display in a program considerably easier than it is in other versions of the language.

In these and other respects the Commodore incorporates almost all the specifications of the Vic-20. But it would have to be more than just an expanded Vic to justify a price of nearly £350 including VAT. Sprite graphics and a powerful sound generator are the features which supply the difference and lift it into the BBC Micro class.

The sound facility is at least as extensive as the BBC Micro’s and, arguably, easier to use. Rather than being embedded in sound and envelope commands, sound control is obtained by Poking values into specific memory locations. The 22 sound-memory locations allow you to define notes in up to three voices with a range of eight octaves. Each voice can be set to one of four wave-forms – triangle, sawtooth, pulse or noise. The attack and decay and sustain/release parameters affect the way the volume of a note develops and fades.

Like the BBC’s generator, the sound facility approaches that of a full sound synthesiser. A fairly close simulation of instruments such as the piano and harpsichord can be achieved as well as a variety of sound effects – the sound of jet engines, gunshots, wind, surf, snare drums, cymbals are some of the possibilities mentioned in the provisional manuals.

Sprites are user-definable shapes which can be moved around a 320 by 200 dot screen. The term was coined by Atari which offers a similar feature on its microcomputers. A sprite object is defined on a grid 24 dots wide and 21 dots long; up to eight of them can be controlled at a time.

Fun with sprites

The video-display chip handles the writing and deleting of the shape on the screen. All the user needs to do to move a sprite is Poke new X and Y co-ordinates into the sprite register.

It is also possible to expand sprites, change their colour, and make them pass behind or in front of other objects on the screen. Two locations in the register can be read to detect potential collisions between sprites or other background objects. Clearly sprite graphics will be useful for games applications, particularly since they can be displayed on the ordinary screen with many other text and graphic characters, as well as in the high-resolution mode. It is not difficult, for example, to program a flock of sprites to pass behind the lines of a program listing – a rather bizarre sight.

The ability to read the entire character generator from ROM into RAM is a boon to the Vic user which makes up for some of the machine’s deficiencies and provides a limited high-resolution facility. Not only does the 64 share this flexibility, but it also supplies a separate high-resolution mode. You can open a screen with a resolution of 320 by 200, which is bit-mapped to an 8K screen and leaves 24K RAM available to the user.

But it is a little misleading of Commodore to claim that the standard 64 offers high-resolution graphics since the Basic does not contain any line or point-plotting commands. Poking to screen memory would indeed light up a pixel; but locating a single dot on the screen is complicated by the fact that the bits in memory correspond to eight by eight blocks rather than successive rows of dots.

Promise for the future

A true high-resolution plotting facility on this machine will have to wait for the arrival of a language, which supplies commands like Plot, Circle, and Paint. Such a language is Simons Basic, which will furnish the resident Basic with refinements such as If-Then-Else, definable procedures and error-trapping found in more advanced Basics. This development will enable full use of the 64’s ample memory capacity – 38K user RAM. One of the eight other possible memory configurations releases 52K for machine code or other languages.

Conclusions

  • The addition of sprite graphics, high-resolution mode and a very effective sound generator to the Vic’s specification make the 64 a very different, far more powerful and versatile machine.
  • Like the Vic, the 64 will profit from a large range of cartridge-based software – as much of it for business applications as for games.
  • It will be able to take advantage of much of the software and accessories for the Pet and the Vic, while cartridges for the Max – also known as the Vic-10 – are compatible with the 64.
  • The 64 is let down by a rather limited Basic. The forthcoming Simons Basic should make good this failing, although it will up the price by at least £50.
  • In respect of its other features the 64 is an excellent machine which can be highly recommended.

First published in Your Computer magazine, October 1982

Review MPF-II

MPFII_Main001

Tim Langdell discovers whether the 64K MPF-II really is an Apple at far less than half the price.

Taiwenese Multitech has pushed a new contender into the £200 colour-computer arena. Its MPF-II is a 64K 6502-based machine with six colours and a Basic which bears far more than just a passing resemblance to Applesoft. In fact the MPF-II is almost identical to a 64K Apple II – but without the expansion potential – and will run most Apple software.

About 32K of RAM is available to the user, and a further 16K or so is required for the video pages. It uses 16K of ROM, which again seems very similar to the Apple II. Indeed the few Calls we made to the ROM produced the same results as on our Apple. For instance, Call -932 cleared the screen, and Poking location 33 enabled us to set the line length to any given value.

Positive keyboard

The MPF-IIs unattractive casing is flat and light-grey, about 7in. wide by l0in. deep, by about 1in. high – it is rather like an Apple in a Spectrum case. The keyboard is of the calculator type, although it has a more positive feel than many on the market. Multitech claims an inexpensive add-on typewriter-quality keyboard is also about to be released.

As soon as you begin to work with the MPF-II its similarity to the Apple becomes apparent. There are three modes: text, low and high-resolution graphics. The text mode is black and white only, but six colours are available in either of the graphics modes. The lower-definition graphics mode has a resolution of 40 by 40, while the higher is 280 by 192. The MA command moves the screen memory to another location, and there is a choice of two high-resolution screens. The first leaves four text lines at the bottom of the screen: the second leaves just one line for, say, error reports.

The MPF-II has a full QWERTY keyboard with larger keys for Return, Space, Control and Shift. There is also a reset button, which is set precariously close to the 0 key, and four cursor keys. The keyboard is uncluttered, but hides many secrets.

Use of templates

The first of the two templates supplied with the machine reveals that the keys provide a full range of graphics functions, accessed by pressing CTRL B followed by any key. There are a total of 49 graphics ranging from a variety of line-drawing aids, through block graphics, to hearts, clubs, diamonds and spades.

The second template presents the surprise; pressing Shift and CTRL at the same time – they are conveniently adjacent – along with another key produces a full key-word on the screen. Thus you can type words in the normal manner, as well as use the Sinclair approach of single-key entry. Offering both is an excellent idea, and using templates instead of cluttering the keyboard is ingenious.

At the back of the MPF-II are sockets to attach either a domestic television or a video monitor. There are also Mic and Line sockets for your cassette recorder, and one for an AC plug. On the left-hand side is a printer interface, a plug-in ROM socket and a labelled RCB.

This socket is for the £10 Remote Control Box – or either a Chinese-character generator, an additional keyboard, or an £80 speech synthesis and sound-generation box.

The MPF-IPs Basic is excellent and, as stated, virtually identical to Applesoft. It may well represent the most powerful Basic available with a machine which costs less than £200. Table 1 gives a list of the key-words.

Capacity for graphics

Although the MPF-II can use only six colours, it can plot them in even the highest resolution. This is in contrast to all the other sub-£200 computers on the market which either limit the number of colours available in the high-resolution mode to two, or only allow definition of colour by character squares – for example, the Spectrum.

The MPF-II is thus capable of very good colour graphics in a limited range of colours. This is enhanced by an excellent facility again, as offered on Apples – to be able to draw shape tables in memory using Draw, XDraw, Rot, Scale and SHLoad.

With these commands you can display a defined shape in memory on the screen, either as it was written into memory, or scaled up or down, or rotated through a given number of degrees, or drawn in the complement colour – XDraw. In addition it is possible to load such shapes onto cassette or disc and recall them again astounding abilities for such an inexpensive computer.

The Basic contains all the standard data and variable handling key-words along with such unusual but very useful commands as OnErr Goto – when an error occurs a Goto is executed – On Goto, and On Gosub. The two graphics resolutions are set by either GR for low resolution or HGR for high.

Drawing lines and plotting points are easily produced with commands such as Plot, VLin, HLin – drawing horizontal and vertical lines  – and Scrn which returns the colour code of the point defined. The printer can be switched on or off using PrtOn and PrtOff – and one presumes that these two replace the more extensive Prt# commands on the more expandable Apple II.

The ability to delete blocks of lines from programs using Del is welcome, but the Basic sadly lacks a renumber routine. Screen editing, Multitech claims, is possible by moving the cursor to the line on screen with an error and retyping it. However this full screen-editing facility did not seem to work on the review version.

A rather interesting plus for those used to other inexpensive microcomputers is the fact that like the Apple the MPF-II has a built-in monitor which can be Called from Basic. Once Called, memory locations and register situations are displayed. With simple one-key commands you can disassemble any area of the memory map into 6502 mnemonics.

Hex dumps are also possible, and there is also a facility for testing areas of RAM for certain bytes, moving bytes in blocks to other locations, and reading and writing machine code to tape or disc. Multitech has included two such systems, one for its own system, and one compatible with the Apple II.

Although sound is clearly possible with the MPF-II, directions on using it are not given in the manual. The useful Diagnostic Nurse supplied with the MPF-II runs a check on most aspects of the machine, including a display of its sound capabilities, which are essentially duration and pitch variations. Like the Apple, the MPF-II has a Trace facility to aid debugging. Unlike the Apple II the MPF-II is not expandable, but it will soon have a disc drive, the speech synthesis and sound-generation board mentioned earlier and Pascal and Forth. A Chinese-language unit has already been produced which allows Chinese-speaking users to work in the Dragon symbol system. Excellent plug-in ROM games are available, and the Invaders and Bridge provided with our system were of excellent quality. A £110 printer will also appear soon, producing 150 lines a minute in a 40-character-per-line format.

Conclusions

  • The MPF-II offers excellent value at around £200.
  • The fact that it is compatible with the Apple II means that an enormous amount of software is already available for it.
  • It is the only £200 microcomputer with true high-resolution colour graphics, and offers a Basic which until now is to be found only on machines as expensive as the Apple II or a BBC Micro.
  • The excellent idea of having the option of either single-key entry or normal entry of key-words should mean that the MPF-II satisfies everyone.
  • It would make an excellent training machine, especially with its good, built-in monitor, but also a good
    home computer for the game player or a low-cost computer for the small businessman.
  • Clearly, anyone who has been attracted by the Apple’s facilities but not by its price will seriously consider this micro as an inexpensive alternative.
Table 1. Keywords
CHR$, ASC, LEFTS, RIGHTS, MIDS, POKE, PEEK, WAIT, CALL, USR, HIMEN, LOMEN, LIST, LISTx,y, DELx,y, REM, INPUT, INPUT” “, GET, DATA, READ, RESTORE, LET, DEF FN, GOTO, GOSUB, IF-THEN, FOR-TO-STEP, RETURN, POP, ON GOTO, ON GOSUB, ONERR GOTO, GR, COLOR, PLOT, HLIN, VLIN, SCRN, HGR, HCOLOR, HPLOT, HPLOTTO, HGR2, SIN, COS, TAN, ATN, INT, RND, SGN, ABS, SQR, EXP, LOG, PRTON, PRTOFF, HC, CONTROL, MA, MP, LOADT, SAVET, LOADA, SAVEA, LOADD, SAVED, DRAW AT, XDRAW AT, ROT, SCALE, SHLOAD, SPEED, TAB, SPC, POS, HOME, NEW, CLEAR, FRE(O), DIM, VAL, STRS, TRACE.

First published in Your Computer magazine, October 1982

Sanyo PHC Range

sanyo001

Pretty boxes and elegant keyboards – Tim Langdell finds out what is inside Sanyo’s shiny new micros.

By the end of last year the only personal computers on the market were the ZX-81, the Vic-20, and the Atom. Now, less than a year later you have the choice of a dozen machines from all over the world – many offering high-resolution colour and sound.

The Japanese have been noticeably absent from the under-£200 market until now. Sanyo’s launch of three microcomputers is just the spearhead of a new Japanese invasion.

The Sanyos range from a strong Spectrum rival, to a cheap battery-powered pocket computer with an LCD display. All three micros have similar cases and full-size keyboards.

Sanyo’s machines are wedge-shaped like typewriters and are 12in. wide by 6in. deep. The keyboards are a lesson in cheap but efficient design. Sanyo uses a similar rubber matting to the Spectrum underneath the keys but capped with hard plastic. A full-size space bar makes touch-typing possible although a keyboard bleep would have been useful.

Top of the range

sanyo003

Sanyo’s PHC-10 is a battery-powered £60 training computer with a single-line liquid crystal display and no provision for television display. Next up the range is the PHC-20, a 4K RAM machine with no colour capability for about £100. But Sanyo’s real hopes rest on the top of the range PHC-25 with high-resolution colour, user-defined keys and 16K RAM for about £150.

This nine-colour computer with high-resolution graphics has a full QWERTY keyboard, with keys for editing, Escape, CTRL, and graphics. The two Shift keys are double-width, as is the Return key.

The PHC-25 is based on a Z-80A CPU as used on the Spectrum, ZX-81, and early Tandy machines. The PHC-25 is nominally referred to as a 16K computer, but on requesting the free bytes in user RAM a return of about 14K is obtained. In contrast, the Spectrum 16K version really only has 9K, so the PHC-25 could still be considered good value on RAM, anyway.

sanyo002

The PHC-25’s video RAM is separate in memory from user RAM, and the ROM containing the Basic interpreter and operating system resides in 24K. This leaves some 18K of free space in the machine’s memory map.

Sanyo Basic is Z-80 colour Microsoft with a few changes for the specific machine. This is thus virtually the same language as used on the TRS-80 colour computer and Dragon 32. However, like the new Colour Genie, the Z-80-based versions of colour Microsoft seem somehow easier to use than the.6809 (Dragon) version, especially when it comes to defining colours.

For instance, CTon and CToff enable you to switch the cassette player on and off from within a program. Other commands include If-Then, Else, plus the usual Goto and Gosub.

There are other especially interesting commands like On Goto and On Gosub. The PHC-25 can not only draw lines using Line but, as with the Dragon, it can use an almost identical statement to construct a box from the line co-ordinates. It can even produce a filled-in box by the addition of one other letter in the statement. Its repertoire includes Paint, which means that full graphics capabilities are within the PHC-25’s range.

Saving a screen

You can save a screen to cassette, you can directly access the Z-80A’s ports with Inp and Out, you can load data files with Input$ and define functions. You can also Scroll just part of the screen using Console which can create text and graphics windows.

Colour on the PHC-25 is a little harder to use than on a Spectrum and the choices of colours vary with the level of resolution. There are four modes. The first is a text-only mode, the second is a nine-colour, low-resolution mode 64 by 64, the third is a medium resolution mode 192 by 128 with nine colours, and the fourth is a 256 by 192 resolution mode. This has, it seems, only two of three possible colours, white, green and black.

Unlike the Dragon the same commands create the colours locally or globally in all modes, and the same commands put dots of colour on the screen. There is none of the fuss of clearing video pages, but then again the PHC-25 only offers up to two pages compared to four on the Dragon and these must be designated at switch-on. The colour from our test model was sharp, without dot-crawl.

The Sanyo PHC-25 has Escape and CTRL keys on the keyboard allowing you to either Pause, or to stop a program totally.

CTRL functions are also available: turning on and off a printer, changing video pages, and so forth. Using the graphics key lets you explore the massive internal character set of the PHC-25 – over 200 characters and graphics in ROM. In our machine there were 100 or so Japanese characters which will apparently be changed for extra graphics in the U.S./U.K. market.

An excellent feature is the four separate cursor keys and four user-defined keys which with Shift allow up to eight single-entry keywords or commands. These are set up upon switching on to produce useful key-words like Run and Return, List, Print, but can be redefined simply using Key.

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Back shot of the PHC-25

The PHC-25 is clearly not designed for indefinite expansion. It comes with both a video monitor, a domestic TV outlet, a built-in Centronics port, a cassette socket, and a user port of undefined character. A sound synthesiser box allows the PHC-25 to use its extensive Sound and Play commands to the full – it will have a three-channel synthesiser with envelope control. This extension box will also have joystick controls.

In conclusion, this machine is a real competitor to the Spectrum, having 5K more user RAM than the 16K Spectrum for about £25 more. It also has a more powerful Basic and its keyboard is certainly far superior.

The two lower-priced Sanyos enter a market already dominated by the ZX-81. The PHC-10 is a battery-operated microcomputer with an LCD display and no potential for expansion. It is purely a training device, somewhat outclassed by such machines as the ZX-81. It has the excellent full-size Sanyo keyboard, but a maximum RAM of only 4K. Its Basic is a version of Tiny Basic resident on the purpose designed chip used as the processor.

It is easy to type programs into the PHC-10, but you can only see a maximum of 16 characters at a time. However, you can use the four cursor keys to scan through quite easily. Each key has auto-repeat.

The major draw-back is the 4K Tiny Basic. With less than 2K of user RAM, and a very limited range of commands, the PHC-10 would be restrictive even for a beginner.

Like the ZX-80, the PHC-10 can only handle integers. Thus dividing 5 by 3 will give an answer of 1. This is not a micro which will double as a home calculator.

Like the Sharp and Tandy handheld computers – which is the market it is aimed at – it will accept a program in the same way as a larger micro, but Running the program results in one-line-at-a-time display, unless the Return key is depressed. To get it to go through a program automatically you use Pause instead of Print in statements, which produces a display of each line at one-second intervals.

The PHC-10 also produces sound of sorts. A Beep command gives a note of a specified pitch for durations of a tenth of a second to 20 seconds.

Good ergonomics

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The Sanyo PHC-20 keyboard

The PHC-20 shares the good ergonomics of its stablemates but may find it difficult to compete in Britain with the features homegrown micros are offering for £100. The PHC-20 is Z-80A based with 8K of ROM and 4K RAM of which 3K is available to the user. Little thought has been devoted to interfacing the PHC-20 to printers and other peripherals.

Even connecting the machine to a television is not straightforward. The Basic is early Microsoft, characterised by friendly if obscure syntax reports. Instead of the line numbers quoted by a Sinclair the PHC-20 will answer all errors with:

?? HOW
?? WHAT
?? SORRY

Loading from cassettes is quite easy but not trouble free. Although the PHC-20 is quite fast it is severely limited by an integer-only ROM.

Conclusions

  • All the Sanyo machines are well packaged and have comfortable keyboards.
  • At the bottom of the range the PHC-10 is little more than a training machine limited by integer Basic and the lack of a screen-display facility.
  • The PHC-20 is again limited. Users can expect new machines to offer more than 3K user RAM, integer Basic, and black and white display for £100.
  • Sanyo’s PHC-25 offers a good keyboard, 14K of user RAM, high-resolution colour and user-defined keys for about £150.
  • If Sanyo make the PHC range available in the High Street the 25 could be a winner. The British micro industry may be forced to do something about reliability and long delivery times.

First published in Your Computer magazine, October 1982