PDP-11

The PDP-11 is a series of computers introduced in 1970 by Digital Equipment Corporation (DEC).

A loaded PDP-11/23 PLUS

The machine word size was 16 bits. For more information, see PDP-11 architecture.

PDP-11 Models and notes

• PDP-11/20 (1970) - UNIBUS, 16-bit memory addressing (32KiW max)
• PDP-11/05 (1972) - UNIBUS, 16-bit memory addressing (32KiW max)
• PDP-11/10 (1972) - UNIBUS, 16-bit memory addressing (32KiW max)
• PDP-11/15 (1972) - UNIBUS, 16-bit memory addressing (32KiW max), OEM model
• PDP-11/40 (1973) - UNIBUS, 18-bit memory addressing (128KiW max)
• PDP-11/45 (1973) - UNIBUS, 18-bit memory addressing (128KiW max), core memory
• PDP-11/50 (1975) - UNIBUS, 18-bit memory addressing (128KiW max), MOS memory
• PDP-11/70 (1975) - UNIBUS, 22-bit memory addressing (2048KiW max)
• PDP-11/03 (1975) - QBUS, 16-bit memory addressing (32KiW max), first QBUS model, first F-11
• PDP-11/34 (1976) - UNIBUS, 18-bit memory addressing (128KiW max)
• PDP-11/04 (1976) - UNIBUS, 16-bit memory addressing (32KiW max)
• PDP-11/55 (1976) - UNIBUS, 18-bit memory addressing (128KiW max), fast bipolar memory
• PDP-11/60 (1977) - UNIBUS, 18-bit memory addressing, writable control store
• PDP-11/23 (1979) - QBUS, 18-bit or 22-bit addressing depending on backplane
• PDP-11/24 (1979) - UNIBUS, 22-bit memory addressing, first UNIBUS model to use F-11 chip
• PDP-11/44 (1979) - UNIBUS, 22-bit memory addressing, last non-LSI PDP-11
• PDP-11/23+ (1981) - QBUS, 22-bit memory addressing
• PDP-11/73 (1983) - QBUS, 22-bit memory addressing, first J-11 machine, 15MHz, integrated FPU, also first PMI PDP-11
• PDP-11/53 (1984) - QBUS, 22-bit memory, S-box or standard qbus, integrated FPU, integrated
• PDP-11/83 (1986) - QBUS, 22-bit memory addressing, J-11 at 18MHz, integrated FPU
• PDP-11/84 (1986) - UNIBUS, 22-bit memory addressing, J-11 at 18MHz, integrated FPU, 768KiW memory.
• PDP-11/93 (1990) - QBUS, 22-bit memory addressing, J-11 at 18MHz, integrated FPU, 2MiW onboard memory
• PDP-11/94 (1990) - UNIBUS, 22-bit memory addressing, J-11 at 18MHz, integrated FPU, 2MiW onboard memory