Connecting a standard c128 ps/2 keyboard

[mr_DK]

Hello everyone,

For a long time I've been following the midibox forum and website and I'm building a MBLC and I've build a MIDI router (which I still must program) with the capability of selecting every input and route it to every output port you choose on the screen. When I have the front panel and stuff I will send some pictures.

But besides that I'm working on a plan of a MIDI device to control my Nuendo more on the midi part to obtain a better workflow for my works (the MBLC does a very good job for the audio part). It consists of a MIDI compressor/limiter to control my breath controller, some keyswitch patches and a C128 keyboard to give in all my presets and saves (quite a lot).

But I'm a little stuck with the C128 keyboard. As I read somewhere on the forum normally you use a C64 keyboard but I have a lot of these old C128 IBM keyboards. So I screwed one open and had a look if I could discover some things about the matrix used. One thing was rather clear, that there are 16 of the keyboard pins going to some resistors and another 8 to some diods. So I guess it's a 16*8 matrix and I'm thinking of remapping and connecting it to a DIN and DOUT module just as an experiment if I can get this working. But the real question here is if anyone of you has an idea about how to connect the matrix? Must I connect the pins from the resistors to the DIN or the pins of diode to the DIN?

May be I'm just being stupid to make such an easy approach with the diods and the resistors? This would be such an easy way to connect about 101 buttons to a Midibox Project...

I hope somebody out here can help me...

Thanks!

Hans

[stryd_one]

[img width=600]http://staff.washington.edu/rrcc/uwweb/C128DCR/dcrkeybd.gif

Have a schematic ;)

Thanks to this guy: http://personalpages.tds.net/~rcarlsen/

[mr_DK]

Hello back stryd_one,

Thanks for the schematic!

I thought this wouldn't be easy, and it seems I was right...

I'll try to be as clear as possible: I connected one DIN module and one DOUT module to the core (j8 and j9). On the DIN I use 2 shift registers (16 rows) and on the DOUT just one (8 cols). The ground of the keyboard is connected to the DIN module (this comes indeed on 25 pins).

There are diodes placed between the 8 signals going to the DOUT module according to the C64 schematic on the users projects web site.

When I measure voltages, I can measure 5V on one side of every button (so I guess I'm right this far). There is 5V on every pin of the DIN module and on every pin of the DOUT module. I installed the SM_ program (the first version because it mentions rows and columns) but it keeps saying: button pressed on row 1 col 1. Whatever I do it keeps displaying this message.

I have really no clue where I went wrong...

I'm getting a little hopeless...

Thanks

[mr_DK]

Hey again,

Sorry for the stupid questions I post here  :-\ but I'm getting really depressed after sitting a whole night afther the modules and trying to figure out wwhat's going wrong...

Is it right that the scanning of the matrix can be visualized on an ossiloscope connected to the DOUT module? I guess I must see some kind of recangtular wave going from 0V to 5V and when I connect my scope to the DOUT pins of the first shift register I measure some kind of "hum". So may be the settings of the sm_example1_v2b aren't correct for my use. And unfortunately I'm not an expert in asm programming.

Again sorry for the newbee questions I'm posting here...

Thanks for your help!

This seems really a great forum!!