PDP-11/35/40
Introduction
The PDP-11/35 was introduced in 1973. It was priced the same as a PDP-11/20 but featured twice the performance thanks to medium scale integrated (MSI) TTL circuits. The PDP-11/35 and PDP-11/40 were UNIBUS systems and used the same KD11-A processor. The PDP-11/35 is an OEM version of the PDP-11/40. Both models were available in a BA11 chassis. Maximum memory was 256KBytes using MOS (semiconductor) memory modules. Although core memory could also be used but would not allow the full 256KByte space due to the number of cards required.
Similar to the PDP-11/20 and other early DEC minicomputers (PDP-11/05, etc.) both 11/35 and 11/40 models featured toggle switch front end panels. The panels for both models were identical with the exception of the model number embossed on the panel. These computers were highly reliable and found their way into industrial process controllers and were widely used in academia as time sharing systems.
As with other UNIBUS PDP-11 successors to the -11/20, the KD11-A processor also used microcode in ROM for its instruction set implementation.
As an operating system for these computers the RSX-11/M, real time operating system, was a popular choice for systems with 256KBytes of memory. Several interactive users could be supported with RSX. A hard disk was required for interactive use, typically one or more RK05s would be used.
Sample Hardware Configuration
- M7231 - KD11-A - Processor data paths card.
- M7847-DJ - MS11-JP 16KW, 18 bit MOS memory hex width card.
- M7859 - KY-11LB Programmer's console card.
- M7856 - DL11-W Serial Line controller, Real Time Clock for console terminal.
- M9312 - Unibus bootstrap/terminator.
- M8256 - RX01/02 floppy disk controller.
This processor family had several options modules available:
- KE11-E - Extended Instruction Set (EIS).
- KE11-F - Floating Instruction Set (FIS Floating Point).
- KT11-D - Memory Management Module.
- KJ11-A - Stack Limit Register.
- KW11-L - Line Time Clock.
PDP-11/35/40 Guides
| Document Name | Order Part No. | Publication Date | Domain |
|---|---|---|---|
| PDP-11/40 System Manual | DEC-II-H40SA-A-D | NA | HW |
| PDP-11/40, PDP-11/35 (21 inch chassis) System Manual | EK-11040-TM-002 | June 1973 | HW |
| PDP-11/40 System Engineering Drawings | NA | September 1972 | HW |
- Adapted from: Gunkies.org