> I've Googled till I'm blue, but I haven't been able to find it. What
> would be a good cross for a DEC 3639 PNP transistor? Or, failing
> that, what are the specs for this transistor?
>
2N3639. My cross here. It doesn't seem to be picked up by the
search engines for some reason.
http://www.pdp8online.com/pdp8docs/decsub.txt
Thanks everyone who contributed to the PDP-11 backplane discussion
that was a side-thread on the PDP-11/70 board set discussion. I
really had no idea that the backplane in a PDP-11 machine was
essentially a board interconnect and not a "bus" in the typical sense.
Now I understand what's geeky interesting about PDP-11s much more than
I did before. Before that discussion, I was under the impression that
they were all just typical shared address/data busses on those
backplanes. My PDP-11/03 is Q-bus and its more like that than the
PDP-11s that are not the VLSI versions. Thinking about it, it makes
much more sense because the CPU is divided among a large number of
boards and having them all sit on a common bus would be quite damaging
to the performance of the CPU.
So I'm guessing the way you figure out how these various CPUs are
implemented using the boards is to look at the schematics and infer
the connections on the backplane from those?
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://www.xmission.com/~legalize/book/download/index.html>
Legalize Adulthood! <http://blogs.xmission.com/legalize/>
OK, I'm building the bit-serial ALU for my 2N2/256 project. Though
it sounds exceedingly elementary, one design variable I haven't been
able to figure out is what supply voltage I should use.
Does anybody know why the 7400-series TTL used +5V for Vcc? I've
looked at the equivalent circuits for TTL and LSTTL. Maybe I'm
missing something, but it's not immediately obvious to me why such
circuits couldn't operate on, say, 4.5V or 6V. I understand the need
for good regulation to maintain noise margin, but why in 1964 did
Texas Instruments chose 5V in particular for TTL? Was it just an
arbitrary choice, or is there a deeper issue?
-Bobby
Wayne (Teletypeparts at aol.com) posted this on Greenkeys a few days
back, but so far there have been no responses. I don't have my DEC
manual collection handy and my 8/A has a different console connector.
I'm sure that someone here knows the pinout, or where to find that
schematic diagram or manual page (isn't it a W076 card)? Please let
him (or the list) know...
thanks
Charles
>I am looking for the simple wiring diagram to connect a 33 ASR to a PDP 8. I
>have the 6 wire cable with the flat molex connector that goes to the PDP 8.
>The other end is just wire ends. I know that wires 2 go to 33's receive and 2
>to 33's send, the other 2 to the tape reader control, but not which ones. My
>color pairs are black/white black/red black/green if that is
>any help. But if I knew the molex pin layout, I could trace them back to the
>right connection on the 33.
>
>Thanks,
>Wayne.
> Date: Sat, 19 Jan 2008 13:01:25 -0800
> From: dwight elvey <dkelvey at hotmail.com>
> I'm not sure how effective that would be in Z80 code. It looks
> like I'd at least need to do 32 bit coding to keep track of things.
> I'd still need to calculate the remainder when done( I need both ).
> The maximum sector index would be 800 decimal.
Ah, then it's easy:
;* Divide 10 bits by 10.
; ---------------------
;
; Input in (HL)
;
; Quotient in (A), remainder in (L).
;
Div10by10:
ld de,(10 shl 6) ; divisor
ld bc,0701h ; iteration count + 1 for xor
xor a ; quotient
Dtbt2:
xor c ; assume set
sbc hl,de ; subtract
jr nc,Dbt4 ; if no carryout
add hl,de ; add back
xor c ; clear the bit
Dbt4:
rr d ; (carry is clear)
rr e ; shift divisor
add a,a ; shift quotient
djnz dbt2 ; loop
rra ; correct quotient
ret ; a = quotient, l = remainder
That will do it for values of a divident up to 1023. The algorithm
can be extended somewhat by shifting the value of 10 left more places
and increasing the number of iterations.
I haven't tested it out on real hardware, but it should work. I've
also got a divide 32-bits by 10 along the same line, if you're
interested. It's fairly deterministic in terms of cycles; i.e.,
there's not a lot of difference in timing between a dividends of 0
and 799.
Cheers,
Chuck
It looks like in order to get VMS running on my 11/780, I'll need to
find install media for an older version than what I have now. VMS 6.2
seems to be the newest version that will run.
Either a CD image or tape image should work; CD image is preferred.
Pat
--
Purdue University ITAP/RCAC --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
> On Sunday 20 January 2008 00:13, Patrick Finnegan wrote:
> > I also would like to find the diagnostics for my 11/780. Either an
> > IMD image of the RX01 or the actual files off the floppy would work
> > best.
>
> I guess I can add the names of the ones I'm looking for:
>
> EVKAA Hardcore Instruction Test
> ESKAB - ESKAM Microdiagnostics
> ESXBA Bus Interaction Diagnostic
> ESXBB VAX System Diagnostic
> ESCAA Unibus Adapter Diagnostic
>
> Those should give me a good start into figuring out what's wrong,
> hopefully.
>
Pat,
Around 4 years or so ago, I sent Megan Gentry an almost complete set of
11/780 Diags on RX01 with the thought she would make them available. (I
don't have any Vaxen.) You might check with her. I still have a
spreadsheet of what disks I sent to her if you're interested in that.
Gary
I also would like to find the diagnostics for my 11/780. Either an IMD
image of the RX01 or the actual files off the floppy would work best.
Thanks!
Pat
--
Purdue University ITAP/RCAC --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
>Are there any pictures around of the 601 or 611?
>(was one of them a rectangular storage scope with an "erase" button?)
>-brad
>
There are now. Hadn't realized that my vintage computer festival east 2007
pictures weren't online.
http://www.pdp8.net/shows/vcfe07/pics/DSCF0038.shtml
Interdata / PE / Concurrent - which I think recently was bought by yet another company - is only a few miles away from the museum where we hold VCF East. Haven't picked a date yet for 2008, but if there's interest then we can probably get a lecture from our contact there. They donated a bunch of hardware to us.
-----Original Message-----
From: jim s <jwstephens at msm.umr.edu>
Subj: Interesting search on Flickr (really it is on topic)
Date: Sun Jan 20, 2008 7:37 am
Size: 638 bytes
To: "'cctalk at classiccmp.org'" <cctalk at classiccmp.org>
I didn't realize I had a lot of time to kill tonight and put in
"interdata" into flickr.com's search. It hits photos taken at a 2005
reunion which apparently was for Interdata, Perkin Elmer, and
Concurrent ex employees.
Probably from someone on this list, though the name didn't ring a bell.
I won't post it here for privacy's sake in case the people who are
mentioned would like not to be spammed.
There are some nice photos of vintage equipment in the pile, which leads
to other photo collections ...
I have seen others mention lists for Dec equipment as well, but had not
seen Interdata mentioned or searched for.
Jim
