Winchester Disks – All You Need To Know

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More and more business microcomputers now offer a Winchester disk drive as an option or add-on. What difference do these devices make, and are they worth the extra money? Will your software still be compatible? Claire Gooding takes a user’s view.

The name ‘Winchester’ for most people in the computer industry conjures up not a cathedral city in Hampshire but a disk for storing masses of data.

The first generation of microcomputers has accustomed most users to floppy disks: not an ideal medium because of their vulnerability (not to be handled after eating fish and chips!) and the limits on the amounts of data they can hold. The size and capacity of floppy disks has increased enormously since the first versions became common in the mid-seventies, but for many users the capacity of even the largest floppy disks cannot cope with their needs.

People quickly became acquainted with the drawbacks of floppies: their tendency to run out of space, and worse, to announce ‘DISK ERROR’ at the slightest excuse. Serious business use of microcomputers made it essential to provide a more robust and efficient form of mass storage.

The first to produce a form of hard-disk storage were pioneers who were prepared to rig up custom-built hardware and write the necessary software to store and retrieve data – usually in the lowest possible form of language, machine code. Although software houses (who really needed more storage space) could probably cope with such demands, the average end user needed something off-the-peg.

By 1980 Winchester disk technology had moved far enough to provide 8” Winchester disks for micros, although they were highly unreliable. One manufacturer who supplied these 8” disks as an optional add-on to his microcomputer recalled that “at any one time we could be fairly sure that only half of the disks we supplied were actually working – the rest were either winging their way to us or back again after repairs!

Reliable solutions

As always, it didn’t take long for the technology to advance to the degree that within only a couple of years there were far more reliable solutions in Winchester form.

The users who clamoured for mass storage first were those who bad bought Apples and PETs (Commodore) in the first wave of microcomputing. At the time few had envisaged that the PET would become one of the most widespread business tools of its time, but its popularity – and the fact that it ran out of space very quickly – meant that Commodore had to do something.

The solution was the Shark disk, made by Mator. The people who had invested in PETs were resourceful and adventurous on the whole, but couldn’t really be expected to muck about with software – especially machine code – to get their programs to on on the hard disk.

“When Mator was approached with the idea of matching the PET with a hard disk, one of the prime requisites was that it should look like one of the existing drives,” explained David Briggs, Hardware Sales Manager, for Commodore. “That way there would be the absolute minimum of software compatibility problems – if it works on the standard floppy, then it should work with the hard disk.”

Meantime, Apple had found its own solution. First the Corvus hard disk came on the scene, then Apple followed with its own Profile.

Other suppliers developed Winchester bolt-ons for the many Z80-based machines. The only problem which such ‘afterthought’ bolt-ons might encounter was that most of the systems they were bolted to had never expected to talk to a Winchester. So unless the user was prepared to write his own Input-Output routines in machine language, he had to make sure that the manufacturer who supplied the disk also supplied a version of CP/M or whatever operating system was concerned, with the necessary BIOS (Basic Input Output System).

BIOS

The BIOS is a piece of software which allows the operating system to link with specific peripheral devices like disk drives and printers. It would be a pretty silly supplier who didn’t ensure that customers could use his wares, so the BIOS problem is not a great factor – you’ll find someone who can offer you a hard disk option among the many independent suppliers of bolt-on Winchesters which have sprung up in the last two years.

On the whole, moving to a Winchester shouldn’t demand any alteration in your applications programs, the exception being if you have bought a system where the protection built into the programs as a bar to illegal copying, is connected with the physical disk – as in the Silicon Office from the Bristol Software Factory.

It didn’t take long for the other manufacturers to realise that their systems would have an edge on competitors in the market place if they could offer Winchester disks as an option, so that buyers could later expand, even if they couldn’t afford mass storage to start with. By 1981 such configurations were common.

By 1982, not only was the hard disk option common, but manufacturers were striving to improve the service they gave. Not all the space on a Winchester is used up, partly because some sectors are always kept spare, ‘just in case’. Better organisation of data, so that operations are optimised, can mean an improvement on access times and throughput.

NEC offers such an ‘improved’ Winchester with its PC 8000, called DisCache. “What DisCache does is to keep the most commonly accessed pieces of data in a RAM buffer,” explained Marketing Manager for the PC, Alan West. “With this technique the most frequently used bits of data are likely to be in the RAM buffer, so there’s no disk access needed at all.” West describes DisCache as “the most intelligent implementation of a Winchester” because it also deals with the eternal problem of backup.

“DisCache keeps a note of the sectors to which data was written, for example, daily. So that at the end of the day, it’s only a matter of backing up that data, using only part of a floppy. With our system, backup becomes a simple end-of-day/month procedure. There’s a complete management system for recovery, so that it becomes a simple serialised restoration of data: it never needs more than twenty diskettes.”

Backup

Backup is one of the hidden costs of buying a Winchester disk. A complete backup needs as many diskettes as two dozen in some cases, and can be extremely tedious: prohibitively so if there’s a need to make a complete backup every day. The alternative is a tape streamer, which can be pricey.

Just as frustrating, is the rare occurrence of re-formatting when there is a disk problem on the Winchester. “First of all,” said one user, “you have to find the re-format program which you threw off the disk to make space months ago. It’s then that you discover that the re-format – if you find it – is a pig to use with lousy documentation. Of course, it’s so seldom used that you only discover this in real emergencies.”

Nevertheless Winchesters have lots of hidden advantages, too. One of the busiest development areas these days is in operating systems, and manufacturers are looking beyond multi-user systems to networking. Compared to the home computer user with his cassette or floppy, this is computing on a grand scale and couldn’t be envisaged without some form of fast storage and retrieval.

Newer operating systems – especially time-sharing systems like the up-and-coming Unix, tend to assume that their targets run on Winchesters.

Having more storage should also have an impact on the people who are doing the actual development of software applications. Being able to hold data together all on one disk has repercussions on the ‘integration’ of software. Eventually we should see more sophisticated systems which perform automatic updates, or create one-off reports with data from many different files. Relational databases – notoriously power-hungry and greedy for space – become another possibility, and that means that users should be able to make any combination of data items, or delate them, to make the kind of selective enquiry which most present systems are not flexible enough to allow.

Winchesters have already played a vital role in making software development easier, and it’s likely that they will even lead to an improvement in the quality of software… or that’s the theory, anyway.

What is it?

For those with an insatiable appetite for technical explanations, here’s a quick look at how a Winchester drive works.

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A Winchester disk drive is hermetically (airtight) sealed to keep out dust and grime. The recording head ‘flies’ just over the surface of the disk drive on a cushion of air.

The main thing that you need to know about Winchester disks is that they are larger – usually 5 to 10 times the capacity – than the floppies which have been the staple storage medium for most microcomputer users.

The main difference between floppies and Winchesters is that Winchesters are made of hard metallic material – hence the term ‘hard disks’, whereas floppies are just that – if you extract one from its cardboard shield you’ll see something like those flimsy disks that used to be given away with magazines as advertising gimmicks.

The advanced technology used to create Winchester disks not only allows far more data to be packed onto a smaller space, but results in what should be a less troublesome medium than floppies. This is due to the fact that Winchesters are sealed in an airtight casing so that they operate in an immaculately clean environment. This means that the hard disk (in the raw it looks much like a brown LP) doesn’t deteriorate as fast as a floppy disk because it is not subjected to the same sort of wear and tear, caused by dust particles and other abrasive matter. The pros and cons of putting all your precious data on to a Winchester disk are tied closely to that ‘hard’ medium.

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Unlike a floppy disk unit, a Winchester frequently shows nothing on the exterior. Despite this, the level of noise is surprising high.

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Tape ‘streamer’ cartridges are probably the best form of back-up to a Winchester disk, though most people use a floppy drive for reasons of economy.

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New half-height Winchesters can be expected to appear on new microcomputers in a few month’s time.

IBM first developed the technology, and stories abound as to how it came by the name Winchester. Sorry, Anglophiles, but most sources, including IBM, seem to agree that it wasn’t named after a quaint Hampshire city: not directly, anyway. The engineers of IBM’s development team named it after the Winchester rifle because the prototype disk drive supported two disks of 8 megabyte capacity – 6:6. The name stuck.

IBM’s aim was to build an exchangeable disk pack with a very high data density. Previous attempts failed because the task of making the read-write head accurate enough to find the right track was almost impossible when the disk itself had to be exchangeable. The read-write head, which picks up data from the disk, had to be able to find the right track within thousands of an inch. Even if this were possible, the whole arrangement would go out of line as soon as the room temperature changed, because of thermal expansion.

Cushion of Air

IBM solved the problem by doing away with the disk-head alignment altogether. The head assembly became exchangeable, along with the disk. The sensor, which in older technology used to be part of the head assembly, was replaced with information held on the disk itself, and the head ‘flies’ across the disk on a thin cushion of air. The head must never actually touch the disk, which is travelling at about 100 mph – quite fast enough to cause a ‘crash’ which would damage the head and wipe out data.

The aluminium surface of a Winchester disk can be machined flat to a tolerance of around ten millionths of an inch, and the head flies about twenty millionths of an inch above the disk surface: about a hundredth of the diameter of a human hair.

The thinner the cushion of air on which the head flies, the more data can be crammed onto the disk, in greater density. The problems are that flying as close as twenty millionths of an inch, the head stands a fair chance of encountering an almighty piece of dust, or a mountainous flake of cigarette ash. The solution: assemble the whole thing in a ‘clean room’ atmosphere, then seal it for life.

The Winchester’s light low-flying head lands as gracefully as Concorde on the disk’s surface only when the disk is turned off and slows to a halt. As a result Winchester heads don’t need the expensive and unreliable mechanism, (rather like the needle on an automatic record-player) which on older-design hard disks was needed to lift and retract the head before the disk stopped.

So the development of the Winchester opened up possibilities of storing vast amounts of data in fairly robust conditions. It’s hardly surprising, given the technology involved, that the Winchester disk was expensive. But it didn’t take long for IBM’s competitors to get on the trail, and prices dropped as the technology improved.

Practical Use

The first disks were 14” – too large to be of any practical use to microcomputer users. But once the teething problems were over, Winchesters began to look like a very attractive alternative to diskettes. Storage rates of 5, 10 or 20 megabytes began to appear in much  smaller packages. By the end of 1980 8” drives which took up no more space than a standard floppy drive were becoming available in reasonable quantities. The price was relatively high, but the speed and capacity were ten times better than a floppy disk.

As the technology improves, the price is dropping as manufacturers make mechanisms simpler, and capacities have crept up from 40 to 80, and now even 450 megabytes.

The other thing that has changed drastically is the size. Winchester disks now come in even smaller sizes than the 8” drives. The next revolutionary step was the 5” or 5.25” disk drive, pioneered by Seagate, and now the 3.25” disk drives are making their appearance, heralded by Syquist’s prototype, which drew the crowds at the National Computer Conference in the USA in 1982.

Who needs one?

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Until recently, Winchesters were only available as add-ons from third-party suppliers (this Corvus unit is one of the most popular). Now more manufacturers will be offering their own.

Not everybody needs a Winchester disk – but if you have a large database or want an integrated accounts system then a Winchester should be high on your shopping list.

Who needs a Winchester? When you find yourself surrounded by a sea of floppies, when your accounting programs can’t be run without switching and swopping, and when your operating system is forever hung up looking for spare sectors, then perhaps it’s time you considered a Winchester.

It’s the sheer lack of space which drives most users to consider hard disk storage, that, and the fact that having their data on a Winchester gives them a nice warm feeling of safety. The sealed disk appears much less vulnerable than a series of small floppies, which can get bent, have cups of coffee spilt on them, and can very often suffer from disk errors. The business of backing up at the end of the day is also so tedious that many people simply get lazy about it, and come to grief when their floppies pack up.

The other factor that pushes some users to the decision of spending a lot of money on a Winchester disk drive is speed. This can become a crucial factor with a micro which is being used for several different applications in a business environment. Not only does the actual disk access take much longer on floppies, but operators can take an inordinate amount of time shuffling data around to squeeze things in.

If there is some question of implementing a multi-user system then a Winchester comes higher up the list of priorities. Not only is speed more crucial in a multi-user environment, but the volume of data and programs is likely to be so great that the system couldn’t work efficiently without a Winchester.

Database

The other software acquisition which demands a certain amount of hardware investment is a database. The pros and cons of running one’s business on a database are still debated up and down the land in mainframe installations, but for users who are considering a set of applications depending on one set of data, it’s a solution worth consideration.

There are several microcomputer databases (Logica’s Rapport, Pactel’s MDBS) but the use of any of them – or even the data files created to run, say, a stock system, can take up a great deal of space. Depending on the access method used and the number of data items, a large set of files can slow operations down considerably. “All I can say about anyone who tries to run a database off a floppy,” said one user, “is that they must be very, very, patient.”

Nevertheless the collection of your data and its organisation into a database can have some valuable spin-offs, especially to a business user. It opens up the possibility of ‘integrating’ operations. This means that instead of executing each task independently and perhaps only updating one file, updates which have a bearing on one set of data – for example the stock file and the supplier file – can be automatically posted. When creating a report, data from several different areas can be called on, and individual programs can all tap the same data.

There are great advantages in this approach, since expanding operations (perhaps adding a payroll) can use information that is already filed. A business user who wants to make the most of the great amount of information stored in his files can also think about such applications as modelling and forecasting; again, a very space-hungry sort of operation because of the mathematical formulae used to manipulate large amounts of data.

Program Generators

Most of the space needed to run integrated applications, or a database system, is taken up by the tables and pointers which have to be set up as a sort of index to link the various pieces of related data. The more links there are, the more space is needed for the tables.

The other way of creating applications which link together is to use a sophisticated applications generator. These have become very popular in the last couple of years, with products like the Last One, and Personal Pearl becoming almost household names. These can be very effective, but nearly all of them work on the same principle: menus which lead the user through the business of setting up a database, linking data and setting up ‘keys’ on which data is sorted (e.g. customer number or surname), and then actually creating the application.

In this case, not only do you need space for the files you create and the tables and indices that they use, but even more space for the heavy business of generating code. Code, which is generated rather than hand-written, tends to be less efficient because it has to be ‘ready-made’, and it will often take up more space and work more slowly than custom-built programs. If you are planning to use an applications generator then a Winchester disk may well be a necessity, since it is easy to run out of space on floppies when creating only one small system.

Software houses tend to go for mass storage of some sort for the obvious reason that they have far more to store, and will often keep several ‘development’ versions of one program, plus sets of test data.

If you have an accounting system or stock system which has been written specifically to run on a pair of floppy disks, then you should be able to manage quite well without hard disk storage. However, transferring the system to a Winchester will make a difference in speed and efficiency, though it probably isn’t worth the effort unless you plan to expand in some other way.

First published in Microcomputer Printout magazine, April 1983

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