80-Bus News

mechanical incompatiblity between 8″ and 5.25″ disks. Further, unfortunately, there is lack of standardization between the various 5.25″ disk systems themselves. Usually these varying standards have been chosen with care for very valid technical reasons concerned with available disk space. However, it does mean that whilst the programs are compatible, the disks on which programs and data are stored may not be directly transferable from one machine to another.

On the brighter side, these various disk standards do not present much of a problem to software suppliers who are capable of supplying software in almost any disk standard. However, an obscure standard, in an unpopular format is less likely to be attractive to a software supplier, meaning investment in copying software is likely to show a lesser return for the effort involved compared with the popular formats, suggesting that the prices for software in unpopular formats are likely to be a little higher than those in the more popular formats. But usually software houses offset the higher cost of unpopular formats against the more popular formats, and charge a standard price for a given piece of software.

Likewise differing formats do not usually present a problem to end users except where several different CP/M based machines are in use in one situation. In this instance, the machine supplier is often in a position to supply the necessary interchange software and hardware to allow the various machines to be interconnected. In this way only one set of software need be purchased for several machines, assuming the software licences allow multiple copies to be made.

To sum up then, CP/M itself remains transparent to the user, being solely concerned with the efficient handling of the transfer of data and programs to and from the disks. The BIOS handles all the communications with the outside world, which it does to a greater or lesser degree of effectiveness depending upon the ability of the manufacturer of the machine in question. (The effectiveness of the BIOS is a good guide to the quality of support that may be expected from a manufacturer.) The main benefit is the vast choice of standard software available at reasonable prices, brought about by the compatibility that CP/M has introduced throughout the small business system and system development markets.

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