Yet more on -8/m Mem problems

From: <(>
Date: Tue Nov 23 20:13:01 1999

> Forget the pulser, which isn't that useful, actually...

Somehow that doesn't surprise me, and it's actually a relief to hear that!

> (I assume you have a TTL databook giving the pinouts of the common TTL
> chips -- if not, GET ONE!).

I've got a copies of the TTL and CMOS Cookbooks, but suspect I should keep
my eyes open for actual databooks. If needed I think I know where I can
borrow one.

> These sound like the ones that Radio Shack/Tandy were selling. FWIW, I

You guessed it.

> So don't think your logic probe is preventing you finding the fault here.
> It's not. It'll easily do the job.

Don't worry, even though it is from Radio Shack it looks more than up to the
task at hand.

> > >to the entire card. You might look at E24 (8881) and E28 (384). These
> > >chips are quad line drivers and receivers and it's possible for an entire
> >
> > I'm guessing the next step is to also take the logic probe to these, but I
> > don't find any data on these chips...
> Let's sort out the addressing fault first, and I'll then see what I can
> find on these (I must have at least a pinout...)

Hmmm, could that info be in the Logic Handbooks, or Small Computer
Handbooks? I've got a bunch of them. I don't remember seeing chips

One thing, I think E28 is actually a 5384, but it was late last night when I
was looking at the board, and didn't make a note of what the first number

> > >during a write cycle to see if the CPU can pull them low.
> >
> > Was hoping to look into this, but it took so long to figure out the
> > O-scope, that I'm out of time today, gotta be at work in 15.
> You probably don't _need_ a 'scope at this point. You can do a lot with
> just the logic probe and a length of wire....

I figured all I needed at this point was the Logic Probe, I just got kind of
sidetracked checking out the Oscope.

> For example. Put the logic probe on MD0 (MSB) on the backplane and
> deposit 7777. It blips low, right? Now examine that location (assumed to
> be a 'working' location) -- it blips low again.

OK, one quick question on this that I've been meaning to clear up, but think
I've got right. '0' is the component side, and '1' is the back side, right?
The manual seem to cover every other part of finding a specific pin except

Received on Tue Nov 23 1999 - 20:13:01 GMT

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