View Full Version : Zenith Z-100 serial port fixed and CP/M to Windows file tranfer

December 14th, 2015, 02:37 PM

As per the 'Z-100 boot ROM' thread I had a problem with the serial ports (J1 and J2) on my Z-120 all-in-one. I have a CP/M boot disk with ZIMP (thanks Eric!), and a Windows PC with various emulators, such as putty and Tera Term (version 4.88 which has YMODEM). Z-100 has two serial ports, J1 and J2. These are wired in reverse so need a null modem on J2. Using PIP to I could either send data from PC to Z-100 on J1, or from Z-100 to PC on J2. Similarly with ZIMP in terminal mode I could send in one direction, but not both ways comms.

I eventually ran the ZDOS diagnostics, the serial port internal loop back was fine but the external loopback (with a straight 25-way cable from J1 to J2) failed. The diagnostics gave a list of 4 buffer chips to replace, either 75189 (MC1489) or 75188 (MC1488 ). I started with U245 75188, which I replaced with a MC1488 equivalent (have to remove the S-100 card cage to get to it). The diagnostics now passed the external loopback so that was a lucky choice!

I then fired up ZIMP and confirmed in terminal mode both ways comms to the PC worked fine, set to 38400 baud, 8 bits even parity. I then tried file transfers using ZIMP and Tera Term. I couldn't get files from the Z-100 to the PC, but managed to get PC to Z-100 transfers working at 9600.

On PC ran Tera Term and selected File -> Transfer -> YMODEM -> Send and select a range of files (thanks again Eric for the Z-100 file archive)

On the Z-100 ran ZIMP, ran SET command to select 9600, then RB (receive batch) - needed to enter RB again for some reason, then transfers worked fine, both Tera Term and ZIMP happily chugged along, showing file progress. So far just copied WordStar over, works fine!

Any recommendations for Windows software that can receive files from ZIMP please?


December 22nd, 2015, 04:03 PM
Is ZIMP a Zenith-only thing? Or a more general CP/M program?

December 23rd, 2015, 01:05 AM
That would be Zenith IMP I suppose - I have never used IMP (although I have a .com file version for C128 somewhere), but there was a post about IMP last year: http://www.vintage-computer.com/vcforum/showthread.php?44002-High-Speed-IMP-v2-46-Communications-Program-for-CP-M

Edit: Original on Walnut Creek CD, for example, or Simtel archives, e.g. http://www.classiccmp.org/cpmarchives/cpm/Software/WalnutCD/simtel/sigm/vols200/vol272/

December 24th, 2015, 08:34 AM
ZIMP is my modified version of IMP for Z-100 where I bumped up the baud speed tables and optimized the assembly code to support higher baud rates. The core changes were made to IMP v2.46 and are platform-independent so you can modify pretty much any IMP overlay to work with it. I wrote an article on it a couple of years ago here: http://planemo.org/retro/updated-imp-v2-46-high-speed/

You can download the ready-to-use ZIMP binary here (http://planemo.org/retro/downloads/z100/software/cpm/communications/)
All you need is zimp.com from the imp-hs-z100.zip archive. The rest of the files are for compiling the source code. I was able to get serial port transfer speeds of up to 38400. Here is another article (http://planemo.org/retro/serial-port-interfacing-z-100-cpm-2-2/) on serial port interfacing to the Z-100 that might help if you're trying to get serial transfers working for the first time on your Z-100.

Edit: If you're just starting with serial port interfacing to the Z-100, I recommend you start with this article (http://planemo.org/retro/linking-z-100-modern-pc-via-serial/). It's Part 1 of the serial port interfacing series and starts with the Z-100/DOS side of serial port interfacing, but the article provides a list of which serial cables and accessories you need and the best serial port on the Z-100 (J2) to use for interfacing.