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High Speed IMP v2.46 Communications Program for CP/M

ECNeilson

Member
Joined
Jul 21, 2014
Messages
48
Location
Dallas, TX
IMP is a terminal communications program written by Irvin Hoff. It was very popular in it's day but was never designed to handle baud rates much above 9600 bps. I recently modified IMP to make it capable of up to 115k baud rates by optimizing the send/receive paths within the software and updating the baud rate table to support higher baud rates. The reason I modified IMP was so that I could more quickly transfer files over a serial link for archiving. Most CP/M systems have a serial port of some sort so depending on your UART chip, you should be able to achieve serial transfer rates between 19200 and 115k bps on your CP/M system.

My modifications to IMP are platform independent so existing overlays can be quickly modified to take advantage of the higher speeds. I've posted the source code along with example overlays on my website: http://planemo.org/retro/updated-imp-v2-46-high-speed/

I achieved the following speeds on my CP/M systems (Limiting factors are CPU speed and supported baud rates in the various UART chips):
- Kaypro 4/84 - 19200 (hard limit of the GI-8116 baud rate chip)
- Apple II PCPI Applicard with High Speed Serial I/O attachment (115k upload/56k download)
- Heath-Zenith Z-100 - 38,400 bps up/down - hard limit of the 8116B UART chip

All in all, very respectable baud rates for early 80's CP/M systems.

Stay strong CP/M brothers!
 
Hello,

Thank you for the above post from 2014. It could be very useful for me to code some Z80 for GI 8116 baud rate generator with 1015D UART.
Your original link had become defunct. I found your updated and current link and have posted it here for anyone else seeking it:


Thanks!

Shawn
 
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