1771 floppy controller questions

From: Tothwolf <tothwolf_at_concentric.net>
Date: Fri Nov 23 03:21:51 2001

On Thu, 22 Nov 2001, Richard Erlacher wrote:
> From: "Tony Duell" <ard_at_p850ug1.demon.co.uk>
>
> > Most (all?) DRAM testers that I've seen test just the chips/simms out of
> > the circuit. It makes sense, since that way they can drive the address
> > lines, RAS/, CAS/, etc and veryify that the RAM works correctly on all
> > locations, etc.
>
> HP made a series of device testers that live on a test clip that you
> plug on in-situ, and if it's designed for one set of supplies, and you
> hook up another, you may not be pleased with the results. I've got a
> few of those out-of-circuit testers, but the one I thing he (Tothwolf)
> is using is one of the type I'm referring to. It would be a shame to
> damage one, as it can test a soldered-in part without first
> unsoldering it.

The tester set I have is designed for out of circuit use. Both units are
labeled 'ramcheck' and list the manufacturer as Innoventions, Inc.
Houston, TX. The tester supports 64k and 256k according to the label. I
opened up the tester, and found it contains an AMD 8088, a 27C32 eprom,
and a single dram chip, along with a mix of 74LS ttl logic chips. From the
looks of it, I could modify it to support 1024s and likely support older
chips if I design some sort of interface board. The speed checker unit is
designed to be used in-line with the tester (or maybe in circuit?), as it
has a ribbon cable with dip idc header on one end. It has a knob for
voltage selection labeled; Off, 4.5V, 5V, 5.5V, NR. I'm not sure what the
NR stands for, maybe no regulation? The other control is a 16 position
rotary switch (0-15), which is used x10 for speed selection in ns. Its
logic board contains a 7805 regulator, a handful of 74LS ttl, and a few
other chips I'd need to look up in a databook (Possibly a PROM and some
clock generators?)

-Toth
Received on Fri Nov 23 2001 - 03:21:51 GMT