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IMSAI 8080 with Cuter monitor + keyboard issue

Brooklyn

Member
Joined
May 30, 2012
Messages
23
Hi, I have an IMSAI 8080 with:

-MPU-A
-VDM1 output to CRT display
-GDM w/ Cuter monitor ROM
-PIO

I am having trouble getting the keyboard to communicate with the Cuter monitor. I can load the Cuter from C000 without issue, but the keys on the keyboard do nothing. It is plugged in to the top port of the input side of the PIO. Also, the cap lock light and other lights on the keyboard do not do anything. The keyboard is getting 5V. Pictures of the setup are below. I figure it could be a PIO settings/address issue, PIO malfunctioning, Cuter settings issue, keyboard could be malfunctioning. The GDM doc mentions something about using the sense switches to set options before starting the Cuter ROM but doesn't give any details further.

Any ideas or thoughts? I have a logic probe and scope.
 

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Hi,

I would suggest asking Mike Douglas or posting in the S100 Google Group ...




Nice big photos ... got any more? One of each board after the setup is complete and working?

I have some of the 5-board setup and hope to build a Processor Technology Subsystem B myself.

I'm still looking for the GPM and 3P+S boards.

I want to sell or trade these boards;
Estimated Value
2x ADS PROM Blasters (UnTested) $100ea.
CompuPro Interfacer II (UnTested) $150
CompuPro Vector Godbout RAM17 board Tested Working $500
DynaByte 16K Static RAM Tested Working $150
IMSAI RAM-4A Rev2 Static RAM (Needs help) $100
ITHICA Audio IA-1100 Composite Video (UnTested) $100
Jade Computer Products Serial/Parallel Interrupt board (UnTested) $150
MITS 88-S4K (Bare Board) $50
TeleTek SBC-1 Z80 CPU board + Original Manual (UnTested) $300
Vandenberg Data Products 16K Static RAM Tested Working $150
XITEX Dallaw SCT-100 Composite Video + Original Manual (UnTested) $100
 
Last edited:
Thanks for the link to the manual, definitely helpful. My GPM has only a single ROM, pictured below. Also, there are some patch cables on the back of both the GPM & PIO. Not sure what they would be for.

The IMSAI came with these cards set up like this, which would make me think it should be compatible, but maybe something got swapped around in the past.

It also has a floppy controller (not installed right now) presumably for booting CP/M. I wonder if the keyboard connected to the PIO was meant for that?
 

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Since it‘s the original CUTER ROM, then the mods to the PIO board must be to make it looks the same to the CPU as the keyboard port on the 3P+S. Generally the 8255s on the PIO would require initialization by the CPU, but they can run in an input mode after reset without further initialization.

If the PIO is configured to look like the 3P+S keyboard port and it’s still not working, it could be a keyboard issue. That looks like it might be a Keytronix keyboard - if so, you can almost guarantee the foam pads are bad and the keys won’t work. What type of keyboard is it?

Mike
 
It is a Key Tronic A65-01696-002P. I’ve heard about the issues with foam and foil, but figured it would work enough to output at least one keystroke? Is there anyway to “fake” a keyboard key press directly on the parallel port signal just to test?
 
Remove the PCB from the key board frame and you can the “type” directly on the PCB pads wih your fingers and that typically works.

Mike
 
Great news, you were right! Apparently the foam & foil had deteriorated enough so that none of the keys worked at all. Disassembling the keyboard and shorting each pad individually allows the keyboard to work. I have already ordered a foam & foil rebuild kit from TexElec.
 

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