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Re: Apple ][+ gravely ill - seeking assistance :(

N.N. Thayer wrote:

On Jun 9, 7:52 pm, "N.N. Thayer" <nntha...@hotmail.com> wrote:


On Jun 1, 9:19 am, "N.N. Thayer" <nntha...@hotmail.com> wrote:



On Jun 1, 8:53 am, schmidtd <schmi...@my-deja.com> wrote:



On Jun 1, 9:22 am, "N.N. Thayer" <nntha...@hotmail.com> wrote:> Hmmm.  Well, now I can get to a prompt and work there indefinitely,


but if I try to load anything off a disk, including ones that I know
are self-bootable, I get garbage characters and the drive simply
spins.



I've swapped disk controller cards, and tested the drives on another
machine, so I know it's not either of those.



Have you swapped power supplies?  Failures might be occurring because
voltages drop too low to sustain life while the drive draws its power
to spin up...



I've got another power supply coming in the mail, a //e model.


Hmm!  Further testing:

1. Swapping power supplies has no effect.

2. If I boot a known good disk with a full onboard bank of RAM, I get
garbage and a constantly spinning drive.

3. If I do the same after having removed RAM E3 through E10, I get a
beep and it drops me into the monitor.  The drive spins down.

4. If I replace E3 through E10 with RAM retrieved from a known working
Language Card, and boot the disk, I get the same result as in #3.



Sorry - for #4 I meant to say the same result as in #2.


Sounds like good reason to suspect the DRAM.

Completely apart from the disk, can you run Applesoft?  Does the
machine function minimally without a disk?  (If it does, then you
can get into the monitor and key in a short memory test program.)

A simple memory test would, for example, write the low byte of
each location's address into memory, then read it back and compare,
then do it again writing the complement of the low byte, etc.

The "easy" way to go is to replace all the DRAM, but I'm guessing
that you don't have that many 4116 chips.

It is unlikely that all 8 DRAMs in a "row" are bad, but you could
have 2 or 3 scattered in more than one bank that could cause this
problem.

-michael

AppleCrate: An Apple II "blade server"!
Home page:  http://members.aol.com/MJMahon/

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