9 Jul
2019
9 Jul
'19
3:43 p.m.
Erom: Eric Smith
Hey, thanks for taking the time to provide all those details.
As you no doubt saw, our emails crossed; I had managed to work out my own
what the difference was. I'd been looking at this page:
http://corestore.org/DEC2065.htm
and saw the two backplanes, and assumed one was the EBox, and one the
MBox - wrong! But eventually I got it straight...
One some other points you covered:
The 1080 was intended to replace a KA10 or KI10 ... It
only needed a
single DTE20 for the internal console PDP-11, and it didn't need an
RH20 because the disk would be attached via an RH10
Got it; makes sense.
Could an -A be upgraded to a -B by swapping the I/O backplane? (Yes, the
wiring to the I/O connectors would have to be changed too, and that might have
been too difficult.) But could the APR handle it (perhaps with one or more
board changes)?
The -PA and -PV designations .. are for the
"arithmetic processor"
(APR), which is the main CPU portion of the KL10.
Useful terminology to know. Do you happen to know what 'PV' stands for -
or is it just a random letter code?
> my new theory is that it's the MBox ... that
is the
> difference between the KL10-A and the KL10-B.
It's not just the MBOX; there are significant EBOX
differences as
well. Various modules from the entire CPU are different, and the
backplane wiring is slightly different. It was possible to upgrade a
-PA to -PV by swapping modules and adding some wraps to the
backplane
Do note I said "KL10-A and the KL10-B", not 'Model A and Model B'... I
assume the APR's in the -A and -B were identical, it was just the I/O
backplane, etc which were different.
On the -PA to -PV upgrade, could the backplane really be done with some
wraps? I ask because I saw in one manual, talking about a KL10-C to -PV
upgrade, it calls for a backplane swap-out.
I've also got some open questions on the later things like the KL10-R, -PW,
and MCA25, which are not covered well in the documentation avilable in
bitsavers; do you know about the later variations?
Noel
9 Jul
9 Jul
4:31 p.m.
On Tue, Jul 9, 2019 at 4:44 PM Noel Chiappa via cctalk <
cctalk at classiccmp.org> wrote:
Could an -A be upgraded to a -B by swapping the I/O
backplane?
Electrically, yes, but physically it might not be easy. The portions of the
chassis that support the backplanes are different, and the power supplies
aren't there.
When I refer to "I/O backplane", technically that's four separate
backplanes. There's one DIA20/DMA20 backplane (not present in all models),
one DTE20 backplane, and two separate backplanes that are combined for the
RH20s (if present), one backplane for the A through D positions (upper 2/3
of each module slot), and one for E and F.
The KL10-A (DECsystem-1080) does not have the RH20 backplanes, and has a
variant of the DTE20 backplane that only supports a single DTE20. The
KL10-A I/O cabinet has only 7 DC power supplies and associated cabling, vs
13 for the KL10-B, because it only has to power one DTE20 rather than four
DTE20s and eight RH20s. Because of that, the KL10-A has only two H742 power
supply frame/front-end assemblies rather than three.
Useful terminology to know. Do you happen to know what 'PV' stands for -
or is it just a random letter code?
Essentially andom, as far as I know. KL10-PB through KL10-PD are assigned
to some kind of subassemblies, but are not the same kind of assembly as the
-PA and -PV. Probably a lot of -Px were assigned before they got to needing
one that became -PV.
On the -PA to -PV upgrade, could the backplane really be done with some
wraps? I ask because I saw in one manual, talking
about a KL10-C to -PV
upgrade, it calls for a backplane swap-out.
I'm not entirely sure, so I easily could have been mistaken. I know -PV to
-PW just needs some wraps. -PA to -PV may have required more significant
backplane changes. Definitely they have different part numbers for the -PA
and -PV backplane assemblies.
I've also got some open questions on the later things like the KL10-R,
AFAIK, -R is functionally and electrically equivalent to -E, but with
physical changes needed for FCC compliance.
-PW,
and MCA25,
The MCA25 is the upgrade from -PV to -PW. It's preinstalled on the 1095 and
2065.
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