Re: Troubleshooting X/Lisa RAM boards - first draft

• On Sat, 3/26/11, James MacPhail <gg__at_email.domain.hidden> wrote:

> From: James MacPhail <gg__at_email.domain.hidden>
> Subject: Re: Troubleshooting X/Lisa RAM boards - first draft
> To: lisalist_at_email.domain.hidden
> Date: Saturday, March 26, 2011, 1:20 PM
>
> >Board 1:
> >00000186    0000 0000 0000 0000 1000
> 0800 0060 0100
> >
> >Board 2:
> >00000186    0000 0000 0000 0000 00FF
> 00FF 00FF 00FF
> >
> >Board 3:
> >00000186    0000 0000 0000 0000 0000
> 0000 0000 2000
> >
> >I moved the board to slot 2, and tried again.
> Obviously, the data in
> >location $186 is different, it now reads:
> >00000186    2000 0000 0000 0000 0000
> 0000 0000 0000
>
> In the first three cases, did you have a good board in MEM
> 1?

In the first three cases, my faulty memory board was installed in MEM1, with a known good board installed in MEM2. The first two boards would prevent the machine from booting if installed in MEM2. In the last case, I simply swapped the board's positions. (bad board MEM2, good board MEM1)

I'm calling the slot closest the CPU board MEM1, and the slot closest the picture tube MEM2, as that's what's silkscreened on the backplane board. This is a Lisa 2/10, ROM version H/88. This is a stock CPU board, no accelerator or mods.

> Another (unlikely) possibility is that your boards are not
> 512K... do
> they have a bunch of wires added to them? If so, they
> (might) have
> been modified to be 2MB boards.

All these boards look factory - no evidence of previous soldering or modifications. And yes, they're the Apple 512k ones :D  

> I'd guess that board 3 has a problem at chip E6 or B6, but
> I'm
> confused about the two/one board factor. Are you calling
> the slot
> closest to the CPU board slot 1?

Yes.

> It's great to have more data!

Yeah! One datapoint does not a study make :D

I'm really intrigued about the one board that came up all 00FF's. I wonder if one of the '373's is bad or something.

-Ian

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