CFOG's PIP, July 1987, Volume 5 No. 9, Whole No. 57, page 6

Further Work with the Run-CPM Z80 Coprocessor for the IBM PC

by Steve Lucius

This article is a followup to one that appeared in the September 1986 PIP on this coprocessor. At the time I was using it with a Cordata PC clone with 2 disk drives. Since then I have added a hard drive with expansion memory board giving me 10 megs of hard drive and 1 meg of memory.

For those who haven't read the original article the RUN-CPM board is a Z-80 coprocessor for an IBM PC or compatible that fits in a short slot. It has it's own built in processor and memory and runs CP/M 2.2. Also included is software to allow using CPM formatted disks in the drives of the IBM PC. I found it quite useful being in many cases faster than my O-1 on the software that it would run. The only problem I had with common O-1 software was Supercalc. I understand there are generic versions of Supercalc available that don't write directly to the screen graphics such as the O-1 version does. Upon further work with it I have had a problem with Wordstar 3.3 with Spelstar and with copying part of one file to a new one using the Wordstar "^kw" command.

One thing left open from the original article was a misconception that I had concerning what could be done with a RAM disk. I was trying to put the RUN-CPM programs on the RAM disk and use the two floppies for CP/M. This cannot be done as the RUN-CPM software needs to access DOS occasionally and that cannot be put on the RAM disk. The result it that with a two floppy system you need to tie up one floppy for the RUN-CPM software and thus only have one to work with. (A second CP/M floppy can be simulated using RAM disk if you have adequate memory.) If you are trying to copy a CP/M disk you need to copy the disk to a RAM disk, then back to the second floppy, a clumsy process.

With the hard drive the RUN-CPM software shines. All the RUN-CPM software resides on the hard drive leaving both floppies available as CP/M disks. (Both must be the same CP/M format, or one MSDOS, thus format conversions must be done via RAMDISK or MSDOS floppy format. This is similar to Uniform.) CP/M programs can also be run from the hard drive using a conversion program. that makes the DOS directories look like CP/M virtual drives. Under CP/M mode at this time I am in drive "L:". The RUN-CPM software converts his to the real directory name of "\CPM2-2\WS3-3\". Needless to say if I weren't using this software I wouldn't have come up with a name like that. The good part about the software is that when I type in the CP/M drive name "L:" the software responds with the MS-DOS directory name.

One problem I have found with operation with the hard drive is that certain programs such as the disk format routine can only be called from the root directory. This may also be a function of the version of DOS that I am using, not the RUN-CPM software. Once you are aware of this problem it is not difficult to get around by either coping with it or using the DOS PATH command to get around it.

In case I forget which drive is which I can pull up a memory resident program to remind me which one is which. Hopefully the chart below will clarify this. The left letter is the drive that CP/M thinks it is. The right hand one is what DOS thinks it is. (Just because the program is on this list doesn't mean it works, just that I want to see if it does. Condor appears to work. Haven't started with FORTRAN yet. Have to transcribe some programs off punchcards to see if it works.)

system last backed up 2/28/87
cpm drives
a: left floppy
b: right floppy
c: hard drive dos
d: ramdisk
e: c:\cpm2-2
f: c:\cpm2-2\db2
g: c:\cpm2-2\mbas
h: c:\cpm22\mbas\games
i: c:\cpm2-2\condor
j: c:\cpm2-2\fortran
k: c:\cpm2-2\nbas
l: c:\cpm2-2\ws3-3
m: c:\cpm2-2\miscdoc
n: c:\newmema
o: c:\newmemb
p: not accessible

Another task I have given the coprocessor is making new member disks. I have the disks stored as CP/M drives "N:" and "0:". Then copying them is a matter of running the CP/M disk formatting routine and using either NSWP or DOS "COPY" to move the data from the hard drive to the CP/M floppy. (NSWP is handy as I can keep the files on the hard disk in a squeezed format and unsqeeze them with NSWP.

The RUN-CPM software also has no trouble with using expanded memory. I am writing this using CP/M WordStar 3.3 in a RAM disk that resides above the 640k of main memory allocated for MSDOS.

One problem that I have with CP/M emulation is general is that DOS does not allow certain characters that CP/M will. I had several unkind things to say trying to convert a CP/M file called "clas5\12.DOC" until I found that "\" is not a legal character for a DOS filename. Had to use "DU" to hack the directory to change the name to "clas5-12.DOC". Why I didn't put the CP/M disk back in the CP/M computer and change the name is a very long story.

An interesting problem is that "NSWP207", doesn't give correct file sizes, but it will move files, squeeze and unsqeeze correctly. [I hope you've found NSWPPC18.ARC by now, Steve! -- bhc]

In summary, the RUN-CPM software and hardware package seems to be well worth the $200 in that it allows a person to use their CP/M software on an MSDOS machine. The legalities of this are another matter.

The coprocessor and software are available from Micro Interfaces Corp, 6824 W. 169th St., Miami, FL, 33015, 305-823-8088.