> On Aug 15, 2024, at 9:44 PM, ben via cctalk <cctalk@classiccmp.org> wrote:
>
> On 2024-08-15 7:39 p.m., cz via cctalk wrote:
>> Eh, it will go for what it goes. Try and keep in mind how tough it was to
>> keep a 1010 running in 1995. Then add 30 years to that.
>> The thought of tracking down a bad flip flop on a thousand flip chip boards
>> really makes me think "yow".
>
> True, but back then things were designed to fixed and tested.
Having the diagnostics available is critical for this. But yes, if you do then
you're right.
It takes me back to 1974, when our college 11/45 crashed and then failed hard
early in the reboot. Called DEC FS. While waiting for the tech to arrive, we
(my classmate Josh Rosen and I) ran CPU diagnostics. Turned up an MMU failure,
failed bit in some CSR. Josh grabbed the engineering drawings to find the data
path in question, and pointed at one chip, saying: "that one". I asked "why
not one of the others?" Answer: "because that's the most expensive chip in the
path".
We told Jim Newport when he arrived what we found, including Josh's blaming a
specific chip. Jim said "we'll see". Soon after he grabbed his soldering iron
and spare chip box to replace -- yes indeed -- the specific chip Josh had
pinpointed.
paul
