28 Sep
2014
28 Sep
'14
9:26 p.m.
From: David Riley
I think most if not all Qbus backplanes were PCBs. But
some of them
(notably the H9270) are PCBs with wire-wrap posts for the connector
terminals. Makes it very handy to, say, modify the H9270 for 22-bit,
which I did .. with no problem.
This reminds me of something I'm looking into. I have a BA11-N (Q18/CD) which
I'd like to upgrade to BA11-S (Q22/CD). (Yes, yes, I know, the -S has a
oomphier power supply, which I won't have, but I'm not trying to run a lot of
power-hungry cards.)
I've tried finding an H9276-A backplane (Q22/CD) to go in it, to replace its
existing H9273-A (Q18/CD), but _every_ place I called which had one listed
reasonably cheap (<$100), and which claimed their internal stock database
(i.e. not just their lame, useless, Web-site) showed they had one... when they
checked the actual shelf, they did not in fact have any.
So now I'm thinking, maybe I'll just add the BDAL19-22 lines to the existing
H9273-A. It doesn't have wirewrap pins, but there's enough pin showing that I
can get two wires onto each pin, and solder them; does not look to be
difficult at all.
I have verified that the CD part of the backplane is identical in both (the
1983-84 Microcomputer Interfaces Handbook, EB-23144-18, has pinouts for the CD
part for both, and they are indeed identical). Alas, I cannot find detailed
data on the rest of the H9273-A: neither the BA11-N Technical Manual, nor the
Print Set, is available online. (I found some old list email which indicates
that someone named David Powell had a copy of the TM - does anyone know him?)
So, has anyone tried to upgrade an H9273-A to H9276-A, and are there any
pitfalls? From what I can see, there shouldn't be a problem, but I'd like
to be 100% sure before I start plugging cards into it...
Noel
28 Sep
28 Sep
10:21 p.m.
I know a lot of people who have wire wrapped their 18 bit backplanes to 22
bit. I also know of RK11-Ds that have been upgraded to either 18 or 22 bit
( I forgot which).
I have backplanes, power supplies, boxes and boards here if you need
anything.
On Sun, Sep 28, 2014 at 11:26 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu>
wrote:
From: David
Riley
I think most if not all Qbus backplanes were
PCBs. But some of them
(notably the H9270) are PCBs with wire-wrap posts for the connector
terminals. Makes it very handy to, say, modify the H9270 for 22-bit,
which I did .. with no problem.
This reminds me of something I'm looking into. I have a BA11-N (Q18/CD)
which
I'd like to upgrade to BA11-S (Q22/CD). (Yes, yes, I know, the -S has a
oomphier power supply, which I won't have, but I'm not trying to run a lot
of
power-hungry cards.)
I've tried finding an H9276-A backplane (Q22/CD) to go in it, to replace
its
existing H9273-A (Q18/CD), but _every_ place I called which had one listed
reasonably cheap (<$100), and which claimed their internal stock database
(i.e. not just their lame, useless, Web-site) showed they had one... when
they
checked the actual shelf, they did not in fact have any.
So now I'm thinking, maybe I'll just add the BDAL19-22 lines to the
existing
H9273-A. It doesn't have wirewrap pins, but there's enough pin showing
that I
can get two wires onto each pin, and solder them; does not look to be
difficult at all.
I have verified that the CD part of the backplane is identical in both (the
1983-84 Microcomputer Interfaces Handbook, EB-23144-18, has pinouts for
the CD
part for both, and they are indeed identical). Alas, I cannot find detailed
data on the rest of the H9273-A: neither the BA11-N Technical Manual, nor
the
Print Set, is available online. (I found some old list email which
indicates
that someone named David Powell had a copy of the TM - does anyone know
him?)
So, has anyone tried to upgrade an H9273-A to H9276-A, and are there any
pitfalls? From what I can see, there shouldn't be a problem, but I'd like
to be 100% sure before I start plugging cards into it...
Noel
29 Sep
29 Sep
12:01 a.m.
On 29/09/2014 05:26, Noel Chiappa wrote:
So now I'm thinking, maybe I'll just add the
BDAL19-22 lines to the existing
H9273-A. It doesn't have wirewrap pins, but there's enough pin showing that I
can get two wires onto each pin, and solder them; does not look to be
difficult at all.
So, has anyone tried to upgrade an H9273-A to H9276-A,
and are there any
pitfalls? From what I can see, there shouldn't be a problem, but I'd like
to be 100% sure before I start plugging cards into it...
Yes, I've done it to a couple. For each BDAL line I used a suitable
length of wire-wrap wire to run the length of the bus plus an allowance
to wind once round each pin. I stripped somewhat over an inch of of
insulation from the end, then used the stripper to separate the
remaining insulation everywhere it would solder to a pin. Soldered one
end, wind once round every succeeding pin, and soldered each. So each
line ends up with a neat and almost straight length of wire. You'll be
able to see the route each has to follow by comparison to the PCB traces
when you take the backplane out.
--
Pete
Peter Turnbull
5:43 a.m.
On Sep 29, 2014, at 3:01, Pete Turnbull <pete at dunnington.plus.com> wrote:
(sorry to respond to a response, but for some reason I don't
see the original around here)
I've done a 22-bit upgrade to H9270, which is a little different
in that it has wire-wrap and it's a 4-slot, serpentine
backplane. The general procedure is basically the same,
though: bus the BDAL18-21 lines together in the same
order that the rest of the lines are bussed on the existing
backplane. Not a lot of work for a whole lot of gain.
I have an H9273 backplane (only, no card cage) that I'm
keeping at 18 bits for the moment in order to be able to
test compatibility of some QBUS boards when I finally
get around to making them. Orthogonal to this conversation,
if anyone has advice on fabricating (or finding) a card cage,
I'm interested.
- Dave
On 29/09/2014 05:26, Noel Chiappa wrote:
So now I'm thinking, maybe I'll just add the BDAL19-22 lines to the existing
H9273-A. It doesn't have wirewrap pins, but there's enough pin showing that I
can get two wires onto each pin, and solder them; does not look to be
difficult at all.
> So, has anyone tried to upgrade an H9273-A to H9276-A, and are there any
> pitfalls? From what I can see, there shouldn't be a problem, but I'd like
> to be 100% sure before I start plugging cards into it...
3504
days inactive
3504
days old
3 comments
4 participants
participants (4)
-
fraveydank＠gmail.com -
jnc＠mercury.lcs.mit.edu -
pete＠dunnington.plus.com -
useddec＠gmail.com