davidc@pyr.gatech.EDU (David Carter) (11/03/89)
In article <285@pacengr.UUCP> tlbaltad@pacengr.UUCP, Tim Baltad gives the
wiring to connect a 2000 keyboard to an Amiga 1000. However, he made a
dangerous assumption about the wire colors in a telephone handset cable.
In fact, depending on which half you use, if you cut one in half as he
suggests, the wire colors may be exactly backwards of the list he gave.
Even worse, this will definitely swap +5 and ground, a very bad thing for
the 2000 keyboard!!
Since there is no way for him or me to know how the colors will end up on
the cable you use, here is the way to tell:
Prepare the telephone handset cable as he describes (the 4-pin modular plug
goes into the Amiga 1000, and the other end is left with wires, stripped to
be soldered onto the 5-pin DIN socket.
Plug the cable into the Amiga, make sure none of the bare wires are touching
anything or each other, and turn on the Amiga. Now measure the voltage across
the OUTER two wires. These should be yellow and black (or black and yellow),
but your cable may not even have colors. In any case, these are the +5 and
ground pins. You should be able to determine very quickly which is which.
Turn off the Amiga and unplug the cable.
Once you know the wires for +5 and ground, you'll know the other two:
KBCLK is the wire right next to +5. KBDATA is the only remaining wire, the
one next to ground. If you do happen to get clock and data reversed, the
worst that will happen is that you get garbage when you try to type.
So the wires in the handset cord are arranged in this >relative< order:
+5 KBCLK KBDAT ground
The 2000's Keyboard Plug is a male 5 pin DIN connector. The diagram here is
looking at the solder side (back) of the female part -- what you'll have to
buy to plug the 2000 keyboard into. On mine, the numbers are written on the
plastic on the back, next to each pin.
2
5 4 Female 5-pin DIN socket,
3 1 looking at rear (solder pins)
6
Pin Signal Description
--- ------ -----------
1 KBCLK Keyboard Clock
2 KBDATA Keyboard Data
3 NC Not Connected
4 GND ground
5 +5v +5 volt power
6 SHIELD shield
So connect the four wires from the handset cable to their respective
pins on the DIN socket. It would be nice to connect DIN pin 6 to some
shield ground on the Amiga, but the keyboard will work fine without it.
Caveat: I have not made this cable myself, but know a person locally who
has. He has not had any problems with his.
David Carter davidc@pyr.gatech.edu