MSV11-R memory module

From Computer History Wiki
Revision as of 23:41, 6 May 2020 by Jnc (talk | contribs) (Note definitely PMI; +warning)
Jump to: navigation, search
MSV11-R card

The MSV11-R (M7458) is a quad-height QBUS/PMI DRAM main memory card.

NOTE: As a PMI card, it uses the CD interconnect; it can therefore only be plugged into a Q/CD backplane. Plugging an MSV11-R card into a regular Q/Q backplane will damage the MSV11-R.

The MSV111-RA (M7358-A) holds 1 MByte when fully populated with 256K DRAMs chips. The memory is arranged as 2 banks, each 16 data bits (1 PDP-11 word) wide, with 2 additional bits for parity (1 per byte). It is a Q22 card.


A single 8-position DIP switch configures the card:

  • Switches S1-S2 select the 22-bit starting address;
  • Switches S3-S4 must always be OFF;
  • Switches S5-S8 select the CSR address.
S1 S2 Staring Address
OFF OFF 00000000 (0 MB)
OFF ON 04000000 (1 MB)
ON OFF 10000000 (2 MB)
ON ON 14000000 (3 MB)

Control Register

Each board has a single control register, which can be configured in the range 17772100-17772136.

S5 S6 S7 S8 CSR Address
ON ON ON ON 17772100
ON ON ON OFF 17772102
ON ON OFF ON 17772104
ON ON OFF OFF 17772106
ON OFF ON ON 17772110
ON OFF ON OFF 17772112
ON OFF OFF ON 17772114
ON OFF OFF OFF 17772116
OFF ON ON ON 17772120
OFF ON ON OFF 17772122
OFF ON OFF ON 17772124
OFF ON OFF OFF 17772126
OFF OFF ON ON 17772130
OFF OFF ON OFF 17772132
OFF OFF OFF ON 17772134
OFF OFF OFF OFF 17772136

Technical information

As far as is known, there are no copies of the engineering drawings extant for the MSV11-R. The following 256K DRAM chips have been observed to be used: MB81256-15 (Fujitsu).

Further reading

  • MSV11-R User Guide, EK-MSV1R-UG