Megalextoria
Retro computing and gaming, sci-fi books, tv and movies and other geeky stuff.

Home » Digital Archaeology » Computer Arcana » Apple » Apple II » Apple III Boot Glitch
Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend 
Switch to threaded view of this topic Create a new topic Submit Reply
Apple III Boot Glitch [message #386613] Sun, 01 September 2019 14:24 Go to next message
Anonymous
Karma:
Originally posted by: Michael Mann

After several years of looking, I finally found an Apple III Plus! It's in great condition, cosmetically, but it doesn't boot to SOS. I'm looking for suggestions to debug it.

On power-up, it generally does not seek the disk drive, and displays a screen full of 'X's with an empty square in the upper, left-hand corner. I think that's where the built-in RAM self-test displays. If you cntl-reset it a couple times and it seeks the disk drive, then it displays the 'X's but with an inverted line in the middle. I uploaded two pictures to Google Photos; I hope this link works:

https://photos.app.goo.gl/dZ7AHtbyrKWe7Zds5

I'm fishing for a more specific method of debugging, other than pulling each chip one by one, and reseating and testing in my little chip tester. BTW, how do you pull off the RAM daughterboard to get at the motherboard chips below it?

Thanks!
Re: Apple III Boot Glitch [message #386621 is a reply to message #386613] Sun, 01 September 2019 18:10 Go to previous message
Michael J. Mahon is currently offline  Michael J. Mahon
Messages: 1657
Registered: October 2012
Karma: 0
Senior Member
Michael Mann <gmail@ware4.com> wrote:
> After several years of looking, I finally found an Apple III Plus! It's
> in great condition, cosmetically, but it doesn't boot to SOS. I'm looking
> for suggestions to debug it.
>
> On power-up, it generally does not seek the disk drive, and displays a
> screen full of 'X's with an empty square in the upper, left-hand corner.
> I think that's where the built-in RAM self-test displays. If you
> cntl-reset it a couple times and it seeks the disk drive, then it
> displays the 'X's but with an inverted line in the middle. I uploaded two
> pictures to Google Photos; I hope this link works:
>
> https://photos.app.goo.gl/dZ7AHtbyrKWe7Zds5
>
> I'm fishing for a more specific method of debugging, other than pulling
> each chip one by one, and reseating and testing in my little chip tester.
> BTW, how do you pull off the RAM daughterboard to get at the motherboard chips below it?
>
> Thanks!
>

You might try wiggling the connectors from the main board to the DRAM
board. Intermittency there was a common problem on both III’s and III+’s.

--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
  Switch to threaded view of this topic Create a new topic Submit Reply
Previous Topic: Re: apple IIc color monitor
Next Topic: ProDOS port bug report
Goto Forum:
  

-=] Back to Top [=-
[ Syndicate this forum (XML) ] [ RSS ] [ PDF ]

Current Time: Tue Oct 15 17:13:54 EDT 2019

Total time taken to generate the page: 0.00350 seconds