24 Oct
2016
24 Oct
'16
1:48 p.m.
On Oct 24, 2016, at 1:41 PM, Paul Koning
<paulkoning at comcast.net> wrote:
5.2.7. It?s discussing the AC loading as a percentage of the risetime (25ns) to allow for
the
reflections.
Yes, all I?m saying is that folks have been looking at OMNIBUS and QBUS and those are
much simpler electrical environments than UNIBUS. You really need to pay attention to
the fact that UNIBUS is really a set of transmission lines so in addition to critical
levels
and currents you need to worry about the transmission line effects (ie the AC
components).
TTFN - Guy
On Oct 24, 2016, at 4:35 PM, Guy Sotomayor Jr
<ggs at shiresoft.com> wrote:
Sure. But we're trying to understand what is required in order to design
alternatives.
Where do you see the 25 ns spec? I didn't see it (admittedly in a quick scan).
...
OK, I guess my last email didn?t make it. It appears to me that the rise time is set at
25ns.
You need to look at the PDP-11 UNIBUS Design Description document on Bitsavers.
Firstly,
in section 4-1, it specifies which chips to use and recommends not using a whole list of
other
chips. The only recommended chips are: 8640, 8641 and 8881.