Tony Duell ????????:
I've just picked up an HP120 (Z80 CP/M machine) on
Ebay :-). The main
prolem (mentioned in the listing I might add, so I am not complaining) is
that it's missing the keyoard.
The keyboard connector is a 6-pin telephone type socket (RJ12?). A quick
look inside (well, what did you expect) suggests the keyboard interface
is contrlled by an 8041 microcnntroller and that it works at 12V levels
(not RS232, but 0V and +12V). There are +12V and ground pins on the
keyboard socket.
So I am looking for any/all of the following :
1) The correct HP keyoard (anyone know the model number?)
IIRC the keyboard is the same as for the HP-150A & B. I don't recall
the part number. There are two different keyboards: The original which
has sticky keys and the later update which does not. The keys usually
get stuck when pressed and won't go down. This makes it easy to break
the spacebar and other large keys, especially if one is accustomed to
typing on Teletypes and other such mechanical terminals. Silicone lube
helps but no one seems to know whether or not it will cause problems.
2) Details of any other keyboards that can be got to work.
Perhaps some other HP terminal keyboards? I do not recall any having
the same connectors and keyboard layout, though. The 150C keyboard is
not compatible.
3) Technical details of the keyboard interface.
IIRC the keyboard was sent a clock and a signal was returned when a
key was pressed. Which key was pressed was determined by timing. There
are only about 4 or 5 14 or 16 pin DIPS in the keyboard used for
scanning the matrix and sending a signal back to the MCU when a key
was pressed.
I thought it used +5VDC. My HP stuff is unreachable for the moment so
I can't check.
In case it might help, the HP150A/B tehnical manual has all the gory
details. It's part number is 45611-90002. The HP120 came out just
before the HP150 and they seem to have a lot of design in common. They
even look alike.
==
jd
Goto, n.:
A programming tool that exists to allow structured programmers
to complain about unstructured programmers.
-- Ray Simard
--