Re: Very aggravating orig. II problem

[rubywand@aol.com (RUBYWAND)]

In article <xlMFOCj.rogtha@delphi.com>, rogtha@delphi.com writes:

>
>	I have a 1979 Apple II; part of its keyboard will not work at all.
>Pressing RETURN, CTRL, ESC, <-, and -> produces various miscellaneous
>ASCII characters, instead of the functions. Of course I can't run any-
>thing on the machine. Can anyone tell me what might be causing this
>problem? (The characters produced are always the same. RETURN always
>gives me a cursed hyphen!)


    Pressing just CTRL should not produce any output. If it does,  (1)
there is something wrong with the KB matrix-- like a short to some other
key,  OR   (2) the KB controller IC is loose in its socket,  messed up
with spilled Coke, or blown.  All of this stuff is part of the KB
assembly. To get to the KB you must detatch the case from its base,
carefully unplugging connectors from the motherboard.
_______
 
    If you did not mean to say that just pressing CTRL produces an output,
then repairing the problem may be simpler. Somehow, Bit 5 (of bits 0-7) 
is being stuck at "1". This forces RETURN ($8D hex or 1000 1101 binary) 
to become - ($AD  or  1010 1101).

    Look for a bent or missing pin on the 16-pin connectors on the ribbon
cable running from the KB to the motherboard at socket A7-- especially,
check Pin 5 on both connectors. Look for a loose 74LS257 in socket B7
(near the front of the motherboard). Or, the 74LS257 in B7 may be damaged;
or, the socket may be damaged-- especially check Pin 11 of the IC  and
socket.
________

    Possibly, the computer was tossed into a dumpster or otherwise kicked
around. If so, then plugs and IC's may have been carelessly reconnected.
You may have problems in the KB AND in connections/IC's related to KB
output.