On Tue, Jul 9, 2019 at 4:44 PM Noel Chiappa via cctalk < cctalk@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.