CFOG's PIP, October 1986, Volume 4 No. 12, Whole No. 48, page 5

Running CP/M 80 on an IBM PC With RUN/CPM Z-80 Co-processor

by Steve Lucius

While contemplating upgrading from my O-1 and Televideo TPC-1 I had the same problem as many others, that is not wanting to abandon my old software and needing someway to run both CPM and MS-DOS software on the same machine. I had tried the Z-80 emulator program that is on the CFOG I board (Z80MU) on an AT clone and found it a trying experience because of the slowness.

I had read various reviews of CPM emulation with the V-20 chip and most of them complained of the slowness. Also the V-20 only runs 8080 software and doesn't support programs written to take advantage of the Z80 chip that the O-1 and Televideo have.

Then I read a review in Computer Shopper by Ted Drude of an outboard Z-80 co-processor that fits into a short slot in an IBM compatible PC. It was sold with RUN/CPM software which allowed disk and terminal emulation from the PC. All this for about $200. It sounded too good to be true. Based on this favorable review I bought one, with a V20 chip to speed up my XT clone.

In general I'm pleased with my purchase. In terms of speed the co-processor is as fast as the Televideo when using Wordstar, and actually is faster in some things. As an example I'm using a generic version of WS 3.3 that has a full page copyright notice. If I load it up on the O-1 or the co-processor it takes about 2 seconds to display the full page copyright notice. Using the public domain program for the V20 chip that is on the CFOG1 bulletin board it takes 5 to 6 seconds to display the same copyright notice. Another program that I have that does a sort of a long table takes 8 seconds on the Televideo and 4 seconds on the co-processor using BASCOM.

The RUN/CPM sof tware that comes with the co-processor supports 179 disk formats and 97 screen formats. It takes about 40 seconds to change from one disk or screen format to another.

Compatibility is a function of both the co-processor and the CPU used in the PC. I had a MBASIC program that ran on the co-processor when I had the 8088 chip in the PC. When I upgraded to a V20 chip the program wouldn't run. But then some of the demonstration GWBASIC programs stopped working on the V20. Programs that work for me include WordStar 2.2 (even on the B drive), WordStar 3.3, MBASIC, dBase II, NSWP207, Gramatik, and Spell.

I couldn't compile programs in Bascom but I could run them. (But then I never could compile them on the Televideo either, only the O-1.) I couldn't run the O-1 Supercalc. [The O-1 SuperCalc has specific screen calls and won't run on anything else. -- bhc] Also the Econometric statistical package STEM wouldn't run on the co-processor or the Televideo.

Installing the co-processor hardware is the same as any other short card. A couple pieces of paper stapled to the booklet for the RUN/CPM software are included for those who haven't installed cards in their PC. The software installation is covered in the instruction manual.

The software should be run on a PC with two floppy drives or a floppy and a hard drive. I can only comment on the 2 floppy drive method. The directions say you can load the RUN/CPM software into a RAMDISK and then use both floppies for CPM. So far I have been unable to do this. I have however been able to copy disks by copying to the RAMDISK and the copying back to the empty disk.

Error messages can be somewhat cryptic. Typing CIR instead of DIR will receive the error message that CPM commands are not accepted from the DOS prompt. A couple of the other error messages are even more cryptic.

Another benefit to people who like to program in MBASIC is more available memory. The O-1 with 1.44 ROM has about 28k when MBASIC is loaded, the Televideo has about 32k. The co-processor comes up with about 36k available. It will actually run the 747.BAS flight simulator on CFOG1.

In general it is a very useful package that can allow the use of CPM-80 software on a 16 bit machine.This review was written using WordStar 3.3 on the emulator with GRAMMATIK and SPELL O-1 software.

The co-processor and RUN/CPM software are available from Micro Interfaces Corp., 6824 W. 169th st, Miami, FL. 33015, 305-823-8088.