grr@cbmvax.UUCP (11/28/87)
A1000 Keyboard Enhancement
Background:
The A1000 keyboard implements a form of 2-key rollover without protection
for key matrix conflicts. Thus when you try to type "from" while holding
down "f" and "r", you will get "frlom". This is because the first two
key depressions short out a path of the key matrix making appear that both
the "l" and "o" keys are depressed. The newer version of the keyboard micro-
processor used in European A1000 keyboards and all A500 keyboards is cognizant
of these matrix conflicts and inhibits keycode generation when an ambiguity
exists. This processor also implements the keycodes used for the two "euro-key"
positions and the new "()/*+" keys in the A500 numeric keypad.
Disclaimer:
The new keyboard micro-processor is not a direct replacement for the
original unit, therefore this article is directed toward the technically
inclined who don't mind hacking up their Amiga a bit. Installing the
changes will void your machine's warranty, and any problems encountered
become your problems. A service bulletin explaining how to use the
new processor as a replacement for a defective older unit is currently
in preparation, so at some poorly defined point in the future you may
be able to get a service center to make the changes for you, subject to
their normal billing rates.
Parts and Tools:
You will need to obtain an A500 Keyboard Processor 6570-036, P/N 328191-02.
This part is available through normal service channels and lists for $25.
You will need a medium and tiny phillips screwdriver, a soldering iron and
either a solder sucker or some solder wick.
Operation:
Expose the keyboard PCB by removing the plastic cover and FCC shield, and
prying up the plastic insulation sheet.
Carefully unsolder and remove the keyboard microprocessor, which should be
either a Rockwell R10L2-11 or a MOS 6570-033. Note the position of the
pin-1 marking. Install and solder in the new 6570-306 microprocessor, being
careful to maintain the original pin-1 orientation.
The keyboard connector should be connected to the PCB by four wires: black,
red, white and green. Unsolder and interchange the white and green wires.
These wires should connect to the center two positions on the keyboard jack.
Be careful to avoid excessive flexing of the connections as the wires will
break easily where they are soldered to the PCB.
Test the keyboard, then replace insulation sheet, FCC shield and cover.
Problems:
No action, no lights:
Check that the wires to the keyboard jack are intact.
No action, shift lock LED lit or keyboard locks up:
Add two 22 pF ceramic disk capacitors between the terminals of the
crystal or ceramic resonator and ground if these are not already present.
The resonator should be connected to pins 10 and 11 of the keyboard
microprocessor.
Blinking shift lock LED:
ROM or RAM self-test has failed, processor is defective or at least
pretty thoroughly confused.
Keyboard sends periodic apostrophe characters:
The clock and data lines are reversed. Reverse white and green wires as
mentioned above.
Keyboard sends continuous characters:
Some wires of the keyboard matrix are probably shorted. Check for solder
splashes, foreign matter and the like.
Smoke issues from amongst the keytops:
You must have made some kind of mistake. Order one each: P/N 327063-01,
Replacement Keyboard, A1000.
(c) Copyright 1987 George Robbins. Material may be redistributed freely
subject to the provisions that all of the material is included without
changes, and that attribution and this copyright notice is retained.
--
George Robbins - now working for, uucp: {uunet|ihnp4|rutgers}!cbmvax!grr
but no way officially representing arpa: cbmvax!grr@uunet.uu.net
Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)