Setting up a VAXstation
ard at p850ug1.demon.co.uk
Sat Oct 6 17:26:16 CDT 2007
> On 10/4/07, der Mouse <mouse at rodents.montreal.qc.ca> wrote:
> > > I am puzzled by people who want to run old hardware, but who don't
> > > want to learn to repair it to component level.
> > > I can understand why
> > > people want to run the software under emulation (even if that's not
> > > what I want to do), but I am seriously wondering what extra you get
> > > from running the old machien _other_ than being able to fully
> > > understnad and repair the hardware.
> Even back in the day, there were lots of folks who bought PETs and
> Apples and more, that didn't know a single thing about hardware
> troubleshooting and repair - 30 years ago, when it broke, they took it
I think you're somewhat missing the point. I can (alas) understand why
there are people who use currently-available machines (both then and now)
and don't understnand how they work.
I cna understnad why people are interested only in old software, not
hardware, and want to run it under emulation on a modern machine
My puzzlement is with people who want to run the old hardware (not have
to run the old hardware becuase it is part of some machine tool or
something) but don't want to understand what's going on inside. What more
do you get over running the software under emulation?
> One of the more important considerations is where I'd get spare parts.
> I _could_ component-level-troubleshoot a SPARC 2 or a SPARC 5, but so
> many of the components are not generic TTL parts, I wouldn't approach
> the fault with the expectation that I'd be able to locate a
> replacement part except on another similar board. I don't mind
Exactly. 'Another _similar_ board' (my emphasis). The point being the
board doesn't have to be indetical, the same part might be used on
another, more common, board. And even if you do have to take the part
from an indentical board, you could do so from a board that's got a fualt
in aother custom chip, thus either being able to use a 'junk' board or
being abole to fix 2 machines from the same board-of-spares.
I do quite a few reparis on HP handheld calculators. There are very few
standard chips in those. The point is, though, you can often take
processor chips from related machine (the ACT -- Arithmetic Control And
Timing -- chip from an HP21 will repair and HP67, for example).
> replacing SMT parts, but in the case of most of the SMT ICs on a SPARC
> board, I don't know where I'd locate new parts. Removing DIP parts is
> difficult from boards as complex as these; not impossible, but
> certainly lots more difficult than from a 2-sided 1970s micro.
As an aside, the most layers of any PCB I've worked on was 14 (or is it
16, I've seen both figures quoted), and that was in a 1968 machine. The
good news is that all I had to desolder and replace were transistors.
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