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Kaypro Keyboard Konundrum

Dutch,
I was impressed by the specs for the Andromeda AR-32A. Although as you mentioned it would need an $80 adapter to program the 8748/8749 family. I like that it can be self booting from CD and is therefore independent of the operating system although booting from CD may not be an option with old PCs. What is the cable interface? Is it parallel port or USB? For some reason it didn't state.
http://www.arlabs.com/

-Dave
 
dave_m said:
Chuck,
I noticed. I wonder why so cheap when all the other vendors I've seen are between $20 and $40?

From this link below, it appears the 8749, the EPROM version of 8049 came out after the newer generation 8051/8751 family so it could not have been a huge winner and is probably rarer than the 8748. This source also states that that while the 8048 was used in the IBM PC keyboard, IBM switched to the Motorola 6805 for the AT keyboard as it was cheaper.
http://www.cpushack.net/Historyofthe8051.html
Click to expand...

To the best of my recollection, the 8748/49 was never intended as a part that would be deployed out to the field on a wholesale basis. Rather, its primary use was in prototyping and initial field testing. The price differential was substantial enough between the plastic 8048 and the cerdip 8748 that you didn't want to buy the erasable version in quantity.

Given that there's no protptying being done currently for the 8048, anyone with a pile of 8748s is going to be looking at slow sales--or replacement, as in this thread's topic.

Tidbit: On impulse, I decided to open one of my circa-1987 NCR AT-style keyboards (made by Cherry in Germany) . There was an 8049 all right, and two unpopulated positions on the PCB; one for an EPROM and the other for an octal latch. There was also a jumper spot on the 8049 EA pin. So the practice of using an optional EPROM with the 8049 must have been widespread.
 
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Chuck(G) said:
Tidbit: On impulse, I decided to open one of my circa-1987 NCR AT-style keyboards (made by Cherry in Germany) . There was an 8049 all right, and two unpopulated positions on the PCB; one for an EPROM and the other for an octal latch.
Click to expand...
You say you saw a position for only an eight bit latch? I would think there would have to be a latch for 11 bits of address (2K). The upper 3 bits of address comes out on the lower half of Port 2 during an external instruction fetch, I wonder if those address bits are latched in the port? It's been way too long for me to remember.
 
dave_m said:
You say you saw a position for only an eight bit latch? I would think there would have to be a latch for 11 bits of address (2K). The upper 3 bits of address comes out on the lower half of Port 2 during an external instruction fetch, I wonder if those address bits are latched in the port? It's been way too long for me to remember.
Click to expand...

Just a '373 is all that it takes. Here's a sample circuit using an 8039.
 
dave_m said:
What is the cable interface? Is it parallel port or USB? For some reason it didn't state.
http://www.arlabs.com/

-Dave
Click to expand...

The AR-32A is a standard parallel interface. Concerning the adapter, you don't necessarily have to buy it. The manual that they supply with the programmer contains documented schematic drawings for each one. I believe that ARLabs will sell a bare board if you didn't want to build an adapter from the ground up.

Dutch
 
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Thanks for the schematic, it brought back old memories. So the upper three address lines are latched in the port saving a glue part. The MCS-48 chip family was a marvel for its time.
-Dave
 
dave_m said:
Thanks for the schematic, it brought back old memories. So the upper three address lines are latched in the port saving a glue part. The MCS-48 chip family was a marvel for its time.
-Dave
Click to expand...

The higher-end AVRs (e.g. ATMega128, ATmega162...) do the same sort of thing with external memory. Add a '573 and a SRAM and you've got 64K of directly-addressable storage. More if you use an I/O to bank-switch. Something that PICs can't easily do.
 
Alternative keyboard for Kaypro

Alternative keyboard for Kaypro

While I'm waiting for parts to arrive to fix my Kaypro II keyboard, I took the plunge and connected up a Radio Shack TRS-80 Model 100 to act as a stand-in keyboard. It is most successful.

You can read the full details in this blog.

Philip
 
pavery said:
I took the plunge and connected up a Radio Shack TRS-80 Model 100 to act as a stand-in keyboard.
Click to expand...
Philip,
I think you were lucky that the Model 100 does not have true RS232 drive levels of about +/- 10V. That would not have been good for the TTL gate in the Kaypro. From what I can tell, the Model 100 has a simple driver with about +/- 3V so your Kaypro is apparently surviving OK with it although it explains why you had to invert the signal since you do not have a RS232 receiver on the kaypro keyboard interface.

What you should do is to send the signal from the M100 into the Kaypro serial port which has a proper receiver, then pick off the receiver output (U69-3) and jumper that signal to the U71-13 gate input.
-Dave
 
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dave_m said:
Philip,
I think you were lucky that the Model 100 does not have true RS232 drive levels of about +/- 10V. That would not have been good for the TTL gate in the Kaypro. From what I can tell, the Model 100 has a simple driver with about +/- 3V so your Kaypro is apparently surviving OK with it although it explains why you had to invert the signal since you do not have a RS232 receiver on the kaypro keyboard interface.

What you should do is to send the signal from the M100 into the Kaypro serial port which has a proper receiver, then pick off the receiver output (U69-3) and jumper that signal to the U71-13 gate input.
-Dave
Click to expand...

Thanks Dave, just as well guys like you are keeping us cowboys in line! I did consider incompatible Drive Levels (particularly when it didn't work), but when I bypassed the first inverter and it worked - all was forgotten (somewhat foolishly perhaps).

I shall make the change, and rewrite the blog! A bonus of your method is its mechanically elegant - I can simply plug my null modem cable into the Kaypro and just make one jumper. Very neat. New blog is here.

Thank you Dave

Philip
 
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Just to let you all know this thread has a happy ending. My quest for a replacement keyboard came up trumps with a nice guy from New York providing the goods.

My desire for a complete spare keyboard was founded as the replacement too had a few dud key switches. Using my old keyboard for spares, I now have an excellent working unit, with spares to boot.

The replacement keyboard uses an external ROM for the 8049, whereas my original uses the internal 8049 ROM. I've retained this 8049 as if the need ever arises, its ROM could be read out. (It will require the purchase of a special adapter to do this though).

Many thanks to the helpers

Philip
 
Good to hear your Model III now has a desktop vintage companion Philip.

I need to continue my interrupted software collection aquisition with my own Kaypro now it too, has a working keyboard.

Tez
 
Reviving a long dead thread.
Has anyone ever dumped the firmware for the Keytronics Kaypro keyboards?
The keyboards I have access to are all mechanical MaxiSwitch style. Pictures and firmware
on bitsavers/kaypro
Also, it turns out the MAME folks discovered a bug in the firmware and that the kb serial port
runs a little slower than 300baud.

"Some incredibly poorly-written
code in the keyboard MCU depends on the fact that the T register is
updated during S4 then copied to A during S4 when mov a,t is executed.
If it doesn't see zero in this register when mov a,t is executed
immediately before the timer interrupt is taken, it hangs."
 
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