Newsgroups: comp.sys.apple2
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!decwrl!world!jeffb
From: jeffb@world.std.com (Jeffrey T Berntsen)
Subject: Re: Apple II+ Hardware Problem???
Message-ID: <1991Mar27.233329.13287@world.std.com>
Organization: The World @ Software Tool & Die
References: <1991Mar27.154406.2521@ccu.umanitoba.ca>
Date: Wed, 27 Mar 1991 23:33:29 GMT
Lines: 73

umsmit72@ccu.umanitoba.ca (Kenneth G. Smith) writes:


>I was wondering if there is anyone out there who can help me with
>a loading problem I'm having with my Apple II+.  When I boot DOS,
>the Applesoft BASIC interpreter seems to crash as soon as it tries
>to execute any of the lines in the 'HELLO' (DOS 3.3) or the
>'Startup' (ProDOS) program.  Using 'TRACE', I can see that it

[stuff deleted]

>Does this sound like a possible motherboard problem?  I don't
>really want to replace it only to find that it's a memory or I/O
>problem that could be fixed with a simple chip swap.  Why will
>some canned software (AEPro (PRODos) and Bank St. Writer (DOS 3.3))
>run flawlessly, while other programs crash on the first statement?

Sounds like it might be as simple as a loose, dirty, or bad Applesoft
ROM chip.  Open the cover on your ][+.  Look underneath the front ends of
the disk controller & other cards you have there.  You should see a row
of six chips about 2 1/2 by 3/4 inches each.  The five on the right are your
Applesoft ROM's.  The one on the left is the Autostart ROM.  Let's assume
for now that they're just loose.  Make sure the Apple is powered off and
unplugged (just to be safe).  Remove all the cards from the slots, remembering
which ones were where.  With your thumb, firmly press in the center of each
of the ROM chips.  If  you hear a mild pop, the chip was loose and you've 
reseated the chip in its socket.  (If you hear a loud crunch, you've pressed
too hard and your thumb is now on the wrong side of the circuit board. ;-)
Replace the cards the way they were before I coaxed you into messing with
the insides of your Apple.  Plug in the power cord and turn it on.  If the
Apple works, that's all you will need to do.  You may need to do this every
once in a while, depending on the age of your machine.  My ][+ was made in
Jan. 1979 and needs chips reseated about every 2 months.
  If that didn't take care of it, it's time to assume that a loose ROM chip
wasn't the problem.  The next most likely problem is that one of the pins
on the ROM chips is dirty.  You'll need to break into your machine the way
you just did to reseat the chips (power off, unplugged, cards out).  With
a small flat blade screwdriver (jeweler's screwdrivers are perfect for this)
pry each of the chips out of the sockets.  Be VERY CAREFUL not to bend or
break any of the pins.  Don't take all of the ROM's out at once.  That will
eliminate the problem of remembering which one goes where.  Once you have
the ROM out, take a look at the pins under a strong light.  If the pins look
light, bright, or shiny, they're in good shape.  If they're brown, black,
or a powdery white color, they need to be cleaned.  The best cleaner is
the type of cleaner used for cleaning tape heads, as it doesn't leave a 
residue.  The bottles of cleaning solution that come with disk drive cleaning
disks will work fine.  Wet a cotton swab with solution and GENTLY swab the
ROM's pins, both outer and inner sides.  Don't worry about between.  If the
cleaning solution removes gunk (or goop) from the pins, you're all set and can
replace the ROM.  If the cleaning solution didn't work, you can use a pencil
eraser to GENTLY rub the gunk from the pins.  Once you use an eraser, you will
need to use the solution to remove eraser residue from the pins (just
brushing away the crumbs isn't enough).  You should now have a clean ROM.
Replace the rom in the socket you removed it from.  Be sure to line up the pins
with the holes in the socket.  The notch on one end of the chip should
be facing toward the keyboard.  Using your thumb, press the ROM into the 
socket being VERY CAREFUL not to bend any of the pins in the process.
Repeat this process for each ROM.  If, after getting everything together,
you have the same problem, it is likely that you have a bad ROM and will need
to find a replacement.  (But that's another problem.......)  It's also
possible that one of the chips in the area of the ROM's has the same kind of
problem we thought the ROMS might have had.  You can try reseating or cleaning
those.  Concentrate on the ones on either side of the ROM's labeled
74LS138 or 74LS139.  One of those controls the computer's access to the ROM's
(but I forget which one.)  
     Some programs , such as AEPro, some games, etc. work because they don't
use Applesoft at all.

     Hope this was some help!
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Jeffrey T. Berntsen                 | looking for a good .sig
jeffb@world.std.com                  |
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