26 Oct
2016
26 Oct
'16
7:14 a.m.
On Oct 26, 2016, at 7:02 AM, Philipp Hachtmann
<hachti at hachti.de> wrote:
Hi,
On 10/25/2016 10:49 PM, Guy Sotomayor Jr wrote:
I?m saying I won?t use another alternative until that alternative has been proven to work
in large scale systems. I have enough troubles with getting my Unibus systems to work
with BC11A cables (which have always been marginal even ?back in the day?). Too much of
the discussions on Unibus interfacing has been ?hey, I?ll use (fill in the blank) chips I
have, it should work?. I?ll shut up about it when someone does an actual engineered
design.
Secondary chip marked (only reputable vendors).
I currently have ~2500 8641
and several 100?s of the other variants. Assuming 100% good parts, I have
enough stock to build at least 100 unibus boards (total) of various types that I
have planned.
And to forestall any questions on the topic, no I will not be selling any of the
chips individually. They are there to allow me to build/sell the various Unibus
boards.
Very enlightening.
You're hoarding interface ICs with commercial second thoughts while deeming any
usable alternative as not working crap. Sounds quite coherent!
BTW Why isn't there a separate list
"ccbusinterfacechip" where those recurring 8881 discussions can be separated
from the more interesting stuff?
I just can't imagine that it should be a real problem to build working Unibus
equipment without the old chips.
Because AFAIK, no one has done the actual engineering to come up with reliable
replacements. As I said, until that?s done I?ll stick with the old chips.
BTW, with modern designs (i.e. 3.3v I/Os) using the old interface chips is a pain. First
they?re 5v I/Os and 2nd they don?t do tri-state. So you need a 2nd set of interface chips
that are 5v tolerant and convert the I/Os (at least the ones you care about to tri-state.
I spend more board area and parts count on interfacing to the Unibus than actually
implementing what I want. For example, the MEM11A board has 3 active parts that are
actually doing the work, all of the rest of the board and parts (over a dozen) are for
interfacing to the unibus.
TTFN - Guy