RP/M — MAP 256K RAM — SYS — VIRTUAL DISK
by RICHARD BEAL
This issue of 80-BUS NEWS is the first for which I have written an article,
so I would like to start by congratulating the editors on keeping up the best
traditions of INMC NEWS and INMC80 NEWS, by publishing my contributions! In fact
not a word has appeared from me for a year, but I haven’t been completely out of
action during that time, as you will see.
There are four related articles in this issue, and it might help if I
explain how they are tied together. First is the article on RP/M. This is the ROM
operating system for Gemini computers, which has been updated. The article
explains all the changes that have taken place, and how RP/M has been altered to
keep up to date. The latest changes, bringing RP/M to version 2.1, have been
triggered off by the introduction of the MAP 256K RAM card.
The MAP RAM is the subject of the second article, which reviews this
exciting new 80-BUS card and explains how to program it.
The third article announces the latest version of SYS (15.0), which has
grown considerably over the last year, and now supports almost every 80-BUS
configuration you can imagine. How about a Nascom 2 fitted with a Gemini
Winchester hard disk, or, perhaps Micropolis double sided floppy disks (or Pertec
double sided), a standard eight inch floppy, a Gemini video card, and a megabyte
of MAP RAM! With SYS it’s easy, provided a Gemini GM829 FDC controller is in use.
The fourth article, about Virtual Disks, brings together the hardware of the
MAP RAM with the software of SYS. Are Virtual Disks useful or just a desperate
attempt to find a use for too much RAM?
The fifth article (that surprised you didn’t it) is a review of the F.V.
Beeper. It has nothing to do with the others, except that I wrote it. Happy New
LATEST NEWS OF RP/M
by RICHARD BEAL
I noticed a strange thing when I was looking through old issues of the
80-BUS NEWS and INMC 80. Nobody has ever written anything that I can see about
RP/M. There must be lots of people with RP/M in their systems, because most
Gemini GM811 and GM813 computers have been supplied with it, except for those
packaged with disks such as the Gemini and Quantum computers, which have special
boot programs (called SIMON). One reason for this may be that many people have
disk systems nowadays, so they have CP/M and are not interested in RP/M. However
perhaps they give it a passing thought as it boots up their disk for them!
In case you don’t know what RP/M is, let me remind you. RP/M means ROM
Program for Microcomputers. It is a 4K ROM which provides simple monitor program
facilities rather like those in NAS-SYS. However the main feature of its design
is that it provides a programming interface almost identical to that provided by
CP/M. This means that all software developed under RP/M will run under CP/M,
allowing easy migration to disks later. Also, some CP/M software, such as the
Microsoft BASIC interpreter, will run under RP/M. It simply has to be loaded from
tape (or from EPROM).
It is also possible to develop and test software under CP/M which is
intended for use on a ROM based system using RP/M. This could be most useful
where a dedicated control system is being built. For example a Gemini GM811 board
could be used by itself, without video card or disks, to control equipment
attached to its PIO. The sockets on the GM811 would contain RP/M, a special EPROM
designed to control the system, and RAM. Also a terminal could be attached to the