ordered, there was no disc! Further comments on this product next
time, I hope. Overall again we have an ‘industry standard product
being improved further, with particular attention to presentation.
A number of improvements have been made in our implementation of CP/M
2.2 – referred to as our implementation Rev 2.3 (sorry about the
confusing terminology). In particular a compressed version of the
text generation used by the display card (AVC) is available when
graphics is not being used. This allows a maximum CP/M user area of
58K, rather than the 55K of in the previous version. When using
graphics, however, the larger version of the support software is still
required. A new manual accompanies the latest version, describing the
The availability of the large capacity and fast access winchester
discs described above will be of particular interest to many CP/M
users. Not only can larger volumes of data be handled (almost
esential for some of the financial packages) but also the speed of
operation of many of the programs is dramatically increased.
Another feature which can be used to advantage by CP/M users is
virtual disc . This allows additional memory fitted to the 256K
memory card now supplied with most CP/M machines to be treated as a
disc, which of course can be accessed very rapidly. Support for this
option is now included with CP/M as we supply it. Those who require
this facility but were not supplied with it at the time of purchase,
and have registered their CP/M ownership, should contact their dealer
or our Warwick office.
THE BEST OF BOTH WORLDS – NAS-DOS AND CP/M
You do not have to make decision to use only one of the two
operating systems NAS-DOS and CP/M. In an Application Note (AN-0011)
we described how to fit a switch to permit selection between the two
operating systems. Since it is necessary to alter the memory
arrangement in the computer between the two systems the switching
arrangement is not as simple as you might suppose – the original note
required the use of a 7 (seven) pole switch and a considerable amount
of wiring. A better solution was worked out by B & L Microcomputers
who designed a small PCB to fit in the computer which used relays for
the switching, reducing the external wiring to an on/off switch. We
now have an even simpler solution using a PCB fitted with only one
chip, a resistor pack and some diodes, A simple on/off switch again
controls which operating system is selected. This board is available,
with full fitting instructions, from your dealer, or your dealer will
fit the unit for you for a small charge.
Both NAS-DOS and CP/M can be organised to use only half of the
Winchester disc, so that in a switched system you can store both types
of file. Files are not of course compatible between the two systems.
ANOTHER OPERATING SYSTEM – UCSD !
White CP/M has become the most widely used operating system on
microcomputers there ere a number of other systems which are not
limited to implementation on a single make of computer. One of the