DEC PDP-11 MSV11 M7551 MSV11-PF M8067 QBus 1MB MOS RAM Memory Cards Lot 3

DEC PDP-11 MSV11 M7551 MSV11-PF M8067 QBus 1MB MOS RAM Memory Cards Lot 3

This lot includes three Digital Equipment Corporation (DEC) QBus memory expansion cards for PDP-11 systems: two MSV11 (M7551) 1-Megabyte MOS RAM cards and one MSV11-PF (M8067) 128-Kilobyte MOS RAM card with parity CSR. All three cards were pulled from a working PDP-11 environment where they were in active use.

Specifications & What's Included

• Lot quantity: 3 cards total
• Card 1 & 2 — MSV11 (M7551) × 2 units
  • Part number: M7551 (PCB: 5017547-01-CA-P2 and 5017547-01-D1-P2)
  • Board revisions: M7551-CA and M7551 LPWR Digital
  • Bus: QBus (Q-Bus)
  • Capacity: 1 Megabyte (1-Mbyte) MOS RAM per card
  • Parity: 22-bit parity with CSR
  • Memory ICs: NEC D41464C2118-47202 DIP RAM chips
• Card 3 — MSV11-PF (M8067) × 1 unit
  • Part number: M8067 (PCB: 5014500 series)
  • Bus: QBus (Q-Bus)
  • Capacity: 128 Kilobytes MOS memory with parity CSR
  • Board silk-screen: "4MB Q22 MOS MEM PAR"
  • Jumper field: LMNPRS configuration headers present
  • Memory ICs: HM62256, SN74S373 DIP chips
• Form factor: Quad-height QBus card (standard DEC quad format)
• Edge connectors: Gold-finger QBus bus interface, clean and intact
• Each card stored in its own anti-static bag
• Cards only — no cables, manuals, or mounting hardware included

Applications

The MSV11 and MSV11-PF are MOS RAM memory expansion cards for DEC PDP-11 minicomputers using the QBus (Q-Bus) backplane. The QBus was DEC's primary interconnect standard for the PDP-11 family from the mid-1970s through the 1980s and into the early 1990s — a lower-cost, smaller alternative to the earlier Unibus used in larger PDP-11 models. PDP-11 QBus systems that used these cards include the PDP-11/23, PDP-11/23+, PDP-11/24, PDP-11/73, PDP-11/83, and PDP-11/93, as well as MicroPDP-11 and Professional 300 series systems. The MSV11 (M7551) provided 1 MB of 22-bit MOS RAM — a substantial expansion for systems that needed to run larger operating systems like RT-11, RSX-11M, or RSTS/E. The MSV11-PF (M8067) is an earlier, smaller-capacity 128 KB card that was used in earlier or more memory-constrained QBus configurations. These cards are today sought by collectors, retrocomputing enthusiasts, and institutions maintaining legacy PDP-11 systems for industrial control, scientific instrumentation, or historical preservation purposes. Genuine DEC QBus memory cards in working condition are increasingly scarce.