pm@cwruecmp.UUCP (Prabhaker Mateti) (04/01/86)
I had built a detached keyboard for the ST! It uses the original ST keyboard,
original keyboard top cover (bearing the Atari 520ST logo), and a few (new,
but surplus) parts (see below). Hardly any electronics experience needed
for this project. Most of it depends on how well you can construct an
enclosure for the keyboard.
To me, the whole thing looks much classier: the plexiglass I bought was dark
satin brown, and it contrasts perfectly with the STs native color.
So far, it has been in daily use for about 5 weeks without any problems.
The coiled chord from the keyboard plugs into the "main" box, the mouse
(and the joystick, when we have some need for it) plug(s) into the
keyboard housing. If need be, it can be reassembled into the way it
originally was, except for the saw cut made along the deep groove
you find running along the entire width above the function keys and
the 520ST logo.
Connections
-----------
The keyboard plugs into the main board using an 18-pin connector (J12).
These pins are numbered 1 through 18, one starting at the bottom (closest
to the keyboard). Only five of these need go to the board; of the remaining
13 pins, one is a keyway ("pin" 2 which is absent), pin 18 is unconnected,
and eleven send/receive signals from the mouse/joy0 and joystick1 ports:
Mouse J12 Joystick1 J12
------------------- -------------------
Up/XB 1 12 up 1 7
dn/XA 2 10 dn 2 5
lt/YA 3 9 left 3 4
rt/YB 4 8 right 4 3
--- 5 unconnected reservd 5 17
fire/lt 6 11 fire 6 6
+5V 7 13 +5V 7 13
ground 8 1 ground 8 1
fire/rt 9 6 -- 9 unconnected
The main reasons I moved the DB-9s to the keyboard were:
(i) I could not find a coiled chord with 16 conductors (I cannot stand
external ribbon cables).
(ii) I felt the mouse and keyboard should be close.
Alas, a typical phone extension chord has only 4 conductors, and we need five:
J12
---
16 ~reset (generated on the main board)
15 Tx Data (of U21 6850 ACIA)
14 Rx Data (of U21 6850 ACIA)
13 +5V
1 ground
Parts Needed
------------
coiled chord of sufficient length, min 5 conductors
5-, or 6-pin DIN socket and plug
2 DB-9s
1 18-pin plug 0.1in pin separation (can use > 18-pin plug too)
1 18-pin socket (can use upto 20-pin socket)
and some scrap plexiglass sheets.
Construction
------------
Most of it is this "box" making with a few solder connections as indicated
above. To instruct how to do the construction is so tedious that I am
going to suggest the very obvious: Open up your ST, and carefully examine it
until you discover your own way of doing it. Two cautionary remarks, however:
o The plexiglass enclosure should be constructed with precision. My wood-
working imprecision made me ruin a couple of panels before I got everything
accurate to within a millimeter! And the edges should be real straight.
o Underneath the keyboard are a few chips; make sure you allow for them and do
not make the keyboard rest physically on these.
Have fun!
--
prabhaker mateti decvax!cwruecmp!pm
department of computer engineering & science pm@Case
case western reserve university (pm%Case@csnet-relay)
cleveland, oh 44106 (216) 368-2816