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PostPosted: April 13th, 2018, 1:49 pm 
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Joined: March 13th, 2018, 2:43 am
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Location: Western Canadia
I am in the process of getting a PC-98 (9821AP2/U8W) and a PC-88 (just a non-SR MkII) from Yahoo Auctions. Finding keyboards for the PC-98 has been easy, but unfortunately, there are only a few PC-88 keyboards and the bidding for them is fierce (a broken keyboard with missing keys and smoke damage just went for $45).

The connector looks somewhat similar (in crappy auction photos), but I can't find a source for either the pinout or the protocol for the PC88 online (at least in English).

From a very brief look at the source code to the N88 emulator, it seems like there are differences in the key map (since the PC98 keyboard is being translated to the PC88 BIOS keymap) so it seems very unlikely.

Are the PC98 keyboards compatible with the PC88? It would be great to get lucky here.

Is the demand for the PC88 keyboards due to the mechanical keyboard cult? It's my understanding from all the videos I'm finding while searching that they have nice switches, but I'd really rather use the keyboard than admire the switches.

Thanks in advance!


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PostPosted: April 14th, 2018, 10:14 pm 
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Joined: March 13th, 2018, 2:43 am
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Location: Western Canadia
Answering my own question here, but I finally dug up some more detailed information on the PC88 keyboard after figuring out how to tell Google it's OK to return results in Japanese:

https://electrelic.com/electrelic/node/597

Google Translate of Electrelic wrote:
The only IC is SN 74159N, which is commonly found on microcontrollers that do key scanning, but this is the TTL's 74 family of 4-Line to 16-Line Decoders / Demultiplexers with Open-Collector Outputs. That is, the key scan is done directly by the main unit. The number of pins is large.
It is 4 bits to designate a matrix line and return 8 bits. In addition to GND and the power supply of 74159 we need 5 V , I think that it is 14 in total.

It seems like there is actually no protocol at all, and the PC88 itself pokes the keyboard matrix directly to figure out which keys are down. Hopefully a microcontroller is fast enough to emulate this.


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