20 Oct
2016
20 Oct
'16
3:05 p.m.
From: David Bridgham
the right threshold voltage to meet the receiver spec
The UNIBUS spec says the 4 crucial receiver parameters are input thresholds
(high and low), and the input currents (high and low); the crucial
transmitter parameters are the output low voltage (at 50 mA sink), and
the output high leakage current.
Noel
21 Oct
21 Oct
11:41 a.m.
New subject: Unibus disk controller with modern storage
On Oct 20, 2016, at 6:05 PM, Noel Chiappa <jnc at
mercury.lcs.mit.edu> wrote:
Where did you find those specs? I see a Unibus Spec on Bitsavers, but it doesn't
appear to mention the electrical specs.
paul
From: David Bridgham
the right threshold voltage to meet the receiver
spec
The UNIBUS spec says the 4 crucial receiver parameters are input thresholds
(high and low), and the input currents (high and low); the crucial
transmitter parameters are the output low voltage (at 50 mA sink), and
the output high leakage current. 
11:50 a.m.
New subject: Unibus disk controller with modern storage
On Oct 21, 2016, at 11:41 AM, Paul Koning
<paulkoning at comcast.net> wrote:
They exist in various DEC handbooks. I don?t recall which one had them.
The specs are fairly stringent in order to meet the max unibus bus lengths (my 11/40 is
close to max).
TTFN - Guy
On Oct 20, 2016, at 6:05 PM, Noel Chiappa <jnc
at mercury.lcs.mit.edu> wrote:
Where did you find those specs? I see a Unibus Spec on Bitsavers, but it doesn't
appear to mention the electrical specs.
From: David Bridgham
the right threshold voltage to meet the receiver
spec
The UNIBUS spec says the 4 crucial receiver parameters are input thresholds
(high and low), and the input currents (high and low); the crucial
transmitter parameters are the output low voltage (at 50 mA sink), and
the output high leakage current.
12:11 p.m.
New subject: Unibus disk controller with modern storage
On Oct 21, 2016, at 2:50 PM, Guy Sotomayor Jr <ggs
at shiresoft.com> wrote:
Found it. 1976 Peripherals Handbook, page 6-4. It specifies the driver output low
voltage at 70 mA sink, not 50...
paul
On Oct 21, 2016, at 11:41 AM, Paul Koning
<paulkoning at comcast.net> wrote:
They exist in various DEC handbooks. I don?t recall which one had them. On Oct 20, 2016, at 6:05 PM, Noel Chiappa <jnc
at mercury.lcs.mit.edu> wrote:
Where did you find those specs? I see a Unibus Spec on Bitsavers, but it doesn't
appear to mention the electrical specs.
From: David Bridgham
the right threshold voltage to meet the receiver
spec
The UNIBUS spec says the 4 crucial receiver parameters are input thresholds
(high and low), and the input currents (high and low); the crucial
transmitter parameters are the output low voltage (at 50 mA sink), and
the output high leakage current. 
12:14 p.m.
New subject: Unibus disk controller with modern storage
To solve the loading problem a division of Tektronix built their own Unibus
repeater.
We not only had a lot of stuff attached to the Unibus but was in multiple
rack instruments.
We also went with round cables the Tektronix made internally. We also made
our own Unibus
cables and added a few LEDs to the paddle boards, power status was one of
them. Can't
remember what the others were far.
A picture of the first generation of the system
http://www.eetimes.com/author.asp?doc_id=1320717&image_number=1
By the time I ended up at Tek the PDP11 had been renamed CP-1160 and came
in custom
colors of light and dark blue.
The Unibus had to make it from the PDP to a couple of the boxes near the
lower left.
On Fri, Oct 21, 2016 at 11:50 AM, Guy Sotomayor Jr <ggs at shiresoft.com>
wrote:
>> From: David Bridgham
>
>> the right threshold voltage to meet the receiver spec
>
> The UNIBUS spec says the 4 crucial receiver parameters are input thresholds
it
doesn't appear to mention the electrical specs.
They exist in various DEC handbooks. I don?t recall which one had them.
The specs are fairly stringent in order to meet the max unibus bus lengths
(my 11/40 is close to max).
TTFN - Guy
On Oct 21, 2016, at 11:41 AM, Paul Koning
<paulkoning at comcast.net>
wrote:
> On Oct 20, 2016, at 6:05 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu>
wrote:
(high and
low), and the input currents (high and low); the crucial
transmitter parameters are the output low voltage (at 50 mA sink), and
the output high leakage current.
Where did you find those specs? I see a Unibus Spec on Bitsavers, but
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4 comments
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participants (4)
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ggs＠shiresoft.com -
jnc＠mercury.lcs.mit.edu -
paulkoning＠comcast.net -
pete＠petelancashire.com