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Master 512 Forum by Robin Burton
Beebug Vol. 8 No. 9 March 1990

After warnings of doom and gloom for some in the last Forum I thought we should look at items of a (slightly) lighter nature this month.


I'm not sure that the 512 Technical Guide would normally have a section of its own in the Forum, but I've given it one because its being mentioned more and more frequently in your letters lately. In case any newer Forum readers don't know the facts, I should first point out that I'm the author of this particular book, so having declared my interest I can now talk about it and you can ignore me if you think it's an abuse of privilege.

Quite a few of you ordered this book from Dabs Press some time ago and are wondering what happened to it, why it's so long in arriving and indeed if it ever will arrive. As I wrote it, I can of course tell you. At the same time it might be interesting to hear how books are produced and eventually reach the reader. It's not obvious without a bit of thought, but there's a great deal more to it than simply writing a book and sending it to a printer.


I finished the final section of the text last September and it was duly forwarded to Dabs for editing and so on, more of which in a moment. In fairness to Dabs I should at this point say that they'd hoped, even expected that I would be able to complete this part of the job much sooner and had based their advertised publication date on that. Unfortunately, like most of you, I still have to earn a living, and as you'll know this often interferes with things you'd rather be doing, like using the 512 (or even talking about it).

Following this, the text was sent for editing, a job carried out by Sid Day, who you may like to know is also (naturally!) a 512 Forum reader (Hi Sid!). You should understand that editing a book the size of the 512 Technical Guide (400+ pages at the last count) is no small or easy task, but even so Sid had completed the job in about a month. Thus, in early November it arrived back at Dabs ready for typesetting, the next stage in the process.

Typesetting is an extremely laborious, time consuming task, and just like writing or editing a book, there's no way to automate the process. As I said, most of us have to earn a living and Dabs is no exception, therefore typsetting has to be 'slotted in' between servicing orders, answering queries, preparing for and attending shows and generally keeping the business running. Of course also in December comes that great stealer of time, the Christmas break, followed almost immediately by another computer show, this time BETT at the Barbican Centre.

This brings us up to date at the time of writing, but with the added complication that changes have taken place at Dabs over the Christmas period which have definitely not assisted production, rather the reverse. The changes themselves are no secret, but I won't turn the Forum into a gossip column in spite of my occasional excursions into story telling (like this one) so you must either learn the details elsewhere or remain in the dark.

I'm presently (January) expecting the typeset proofs of the book to arrive here any day, when my next job will be to check everything and correct the inevitable errors which will have crept in during editing or typesetting. I shall then produce the glossary and finally write the index and number the contents list, but only when the page numbers are guaranteed not to change again. After that it's back to Dabs for resetting of my late changes or additions.

Assuming this last check doesn't cause page renumbering, all that remains then is a final check of the finished product. When this is complete it's on to the easy part, which is getting the book printed, bound and on sale. Depending on the printer's workload at the time, this usually means between one and two months to first availability on the book shelves.

There you have the complete story. If you ordered the book some time ago all I can say is be patient a little longer. It will appear in due course, hopefully pretty soon after you read this issue of BEEBUG. In answer to those who specifically queried the point, the book has definitely not been either 'shelved' or cancelled.


One other specific query about the Technical Guide which is frequently raised is the question of whether or not it includes a 512 memory expansion project. The answer to this is 'Yes, it does'. The reason for mention of this point is that more and more over the last year or so the 512's limited memory has proved a stumbling block to running new software. Those who've recently acquired a 512 are in many ways worse off than the rest of us because they don't have ready access to 'old' software and never had the chance to buy a PC+ either.

The reason for memory shortage being a more common problem these days is simple. While a 'standard' PC or clone is limited to 640K of memory and 256K or 384K was common only a short time ago, PC systems with EMS (Expanded Memory System) are much more the norm nowadays. While the original 8086/8088 processor chips and their equivalents could only address 640K of memory (which, compared with CP/M Z80 based systems seemed huge at the time), later chips aren't so limited. For example the 80286 can manage a theoretical 16Mbytes of memory. The problem of course is, as usual, the software.

It's interesting to note that, while computers are often spoken of as mere boxes, just convenient containers in which to run the all important software, the truth is that in terms of developments this view is absolutely incorrect. Certainly some programs are better than others, and certainly some are genuinely imaginative or innovative, but the ultimate limit to what can be achieved is always governed by the hardware, primarily the processor chip.

The way that developments actually happen is that processor manufacturers such as Intel or Motorola compete with each other to produce new and more sophisticated processor chips. Following the arrival of such a new chip, the PC manufacturers then compete to produce new and better machines, followed by software producers who write more complex and sophisticated software to take advantage of the new machines. So you see, the truth is that software must always trail the hardware in terms of capability. That's why I always smile when I hear some supposedly informed and expert individual saying "The hardware isn't important, it's the software that matters"!

Back to the point. In 1985, as a result of processor advances, the Lotus Development Corporation in conjunction with Intel announced the specifications for EMS. A while later the Microsoft Corporation announced that Microsoft Windows would be developed to take advantage of EMS. To cut a long story short this was produced for MS-DOS version 3 and EMS PCs. To maintain the compatibility with earlier and more limited versions of both DOS and processor, new extra commands were provided by the processor chip to handle EMS and overcome the previous 640K limit, while retaining all the existing instructions.

If you're unfamiliar with how EMS works, the easiest way to understand it is to liken it to the Beeb's sideways RAM. An area of memory is logically mapped at a fixed location in the addressing range of the machine, but it consists of separate sections or blocks of RAM which can be individually switched (paged) in or out by the processor under software control. In effect, although a PC may still only address 640K of RAM directly, the contents of some parts of that 640K (in a 64K segment known as the page frame) can be swapped with areas of the extended memory in 16K chunks, in effect giving overlaid main memory. To be able to do this though, you need both the correct processor and the correct operating system.

Well written software which can take advantage of EMS while retaining compatibility with earlier systems should check the version of DOS and, if appropriate, the type of machine to see if EMS is available. If not then the program can resort to restricting facilities or file sizes, or overlaying programs or data from disc so that it can still run. Unfortunately though, in some cases it just won't work without EMS.

I've digressed a little as usual, so if you're thinking this isn't much to do with the 512 perhaps I should explain. As processor chips and PCs have expanded their capabilities, applications software has tended to grow in complexity (and memory consumption) accordingly. One implication is that you may upgrade to a later version of a package you already use successfully in the 512 only to find, if you're unlucky, that the new version won't run at all.

Alternatively, if luck is with you, the new package may run well enough, but may also consume a great deal more memory. I've had several letters on this topic and have recently upgraded one of my own applications to find the same thing. The 'old' version of the main program was an 'EXE' file of about 105K, but the new one, (which happily does work perfectly by the way) is all of 226K.

Since an unexpanded 'empty' 512 has about 356K free with DOS Plus 2.1, it's easy to see that the original program left about 250K free, but the new one has just about cut this in half. This needn't cause problems with every package of course, but with mine, for example, one immediate problem is that many of my existing files are now too big to load with the new software. A secondary point is that I can no longer load the on-line help at all unless I haven't yet loaded a file, and using a DOS shell from within the application, for example, to copy a file or to format a disc, is also now a no-go area more often than not. The all too frequently seen response is now 'Not enough memory to load XYZ'.

One possible solution with an application like word processing is to divide files into smaller ones (using the old software) and simply have more of them, but with something like a spreadsheet or a graphics program for example, this is likely to be totally out of the question.

This brings us full circle. Upgrade your software and, even if it runs successfully, it's possible that you'll suddenly become acutely aware of the shortage of memory in the 512. The PC+ has been out of production for over a year now, so apart from occasional secondhand sales that's no help, but as I said earlier, there is a memory expansion project in the book.


Finally, on the same subject there is a possibility of a new ready-made 512 expansion board being produced, but this is a very expensive undertaking and it won't go ahead unless the numbers justify it. Note that THIS IS NOT an advertisement and no further information will be forthcoming just yet even if you ask for it, but if you would be interested just drop me a short note and say so. Your letter might very well increase the chances of this product seeing the light of day.

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