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                 = External Keyboard for an Amiga 1200 =
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                 =           By Hans Luijten           =
                 -    EMail: j.a.w.m.luijten@kub.nl    -
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  WARNING:

Although this is hack is done on several A1200's, and works just great on
these machines, I won't be responsible for ANY damage caused by this hack.


  WHAT YOU NEED:

An external (or internal) keyboard like from an Amiga 2000/3000/4000,
some wire, a plug for the keyboard, a screwdriver, a scalpel , some solder,
a 'fine' soldering iron and a switch.
If you don't have any experience modifying your computer or other
electronics, then this is NOT for you, ask someone who does have experience.


  WHAT WE WILL DO:

We will deactivate the internal Amiga 1200 keyboard MPU and feed the CIA
with the required keyboard signal's coming form the 6570 of the external
keyboard. Since Ctrl-LAmiga-RAmiga won't work with the Amiga 2000/3000/4000
keyboards, we will also build a reset-switch.


  HOW WE DO IT:

First we disassemble the Amiga 1200, if you can't do this: STOP now, this
hack is NOT for you. We need to remove the case, the keyboard, the
floppydrive and (if you have one) the harddisk.
After you did this, you need to remove the tin-cover from the motherboard
so we can access it.

Now take a look at the 'A1200_Inside'-IFF.
We first will deactivate the keyboard-MPU of the Amiga 1200.
We need to cut two lines of the U13, pin 13 and 14. The little dot on the
chip indicates pin 1, or use the IFF to locate these pins.
After cutting these lines the CIA (U7) won't receive any keyboard data
(KbdData and KbdClk).
We can cut these pins 2 using the scalpel. If you use a new sharp scalpel,
this won't be a problem. Remember: be patient and do it gently !!
After cutting, we bend the pins a bit further apart, so they won't make any
contacts. Check this with a magnifying-glass !
The Keyboard-MPU of the Amiga 1200 is now deactivated.

Again look at the 'A1200_Inside'-IFF.
We now will deroute the keyboard-data to/from the external keyboard.
This is done by soldering 2 wires from pins 43 and 44 of the CIA (U7).
In order to locate these pins we can look at the IFF again. The dot on the
chip indicates pin 1. These 2 wires go to KbdDat and KbdClk of the external
keyboard like shown in the IFF.
The Amiga 2000/3000/4000 keyboard will need a powersupply, this can be taken
from the floppydrive's powersupply. From here we take +5Volt and GND.
Remember to use a tester to check if this is really +5Volt and GND !
The other 2 lines of the powersupply are GND and +12Volt, +12Volt will be
fatal for you keyboard and computer !! So be carefull !!
We now have 4 wires which must be connected to the 5 pin DIN plug for the
external keyboard. Look at the 'Keyboards'-IFF for the pin-layout.

At this point the external keyboard will work, but we still can't reset the
Amiga 1200. For this purpose we use a simple switch, which makes contact
when you push it. This will be our reset switch. The switch we find in an
PC-case, for RESET, can be used fo this purpose (if you are building your
Amiga 1200 in a PC-case or PC-Tower!).

Now look again at the 'A1200_Inside'-IFF.
Pin 38 of the keyboard-MPU (U13) is connected to /KbdReset (pin 128 of the
150-pins CPU-Slot). This line and GND must be connect to the switch.
Gently solder a wire to pin 38 of U13 and a wire from GND, connect both
wires to the switch, as drawn in the IFF.

After doing this, you can put your Amiga 1200 together again for the first
testing. We won't need the old Amiga 1200 keyboard anymore, it won't
function anyway.
When you test this hack do the following:

1. take a copy of the Workbench and insert it in DF0:
2. switch the Amiga 1200 on
3. from the workbench: open a shell
4. Try typing, if you get a lot of "'"-signs, then you got KbdClk and KbdDat
   switched. Turn the computer off and switch the lines on the keyboard-plug.
5. Test your reset-switch by simply pushing it.

If you have any trouble; begin at the top of this doc and check everything.

Note: Amiga 1000, Amiga CDTV and Amiga 500 keyboard will work aswell, you'll
      need to lookup the pinlayout of the plugs.

      This entire text is typed with an Amiga 2000 keyboard on my Amiga
      1200, which is build in a PC-Tower!

Note: For creating this hack, I took some the pin-info from the
      hack of Gravan A. McCormack (Tetragon@lisa.apana.org.au).