PDP-11/44
Introduction
The PDP-11/44 (KD11-Z) was introduced in 1980 as a replacement for the -11/45 and -11/70. It had roughly half the processing power of the -11/70. This was also to be the last implementation of a PDP-11 in MSI 74xxx series discrete circuits and the last UNIBUS based processor. Subsequent PDP-11 processors were implemented as VLSI microprocessors and were QBus based.
The switch console panel was replaced with a virtual console run by an Intel 8085 processor on the CPU. It apparently had the most advanced PDP-11 virtual console. The CPU occupied five hex width cards on a 9-slot backplane (DD11-DK). An additional 4-slot expansion backplane (DD11-CK) could be accommodated within the BA11-A mounting box. Dual TU58 tape drives were included with the PDP-11/44 for running diagnostics. A typical PDP11-44/ had the following module configuration:
- M7090 - Console Interface Module.
- M7093 - FP11-F (based on sixteen AMD 2901 bit-slice ALUs)
- M7094 - Data Path Module.
- M7095 - Control Module.
- M7096 - Multi-Function Module.
- M7097 - KK11-B, 8KByte cache memory.
- M7098 - UNIBUS Interface.
- M8722 - MS11-M, MOS semiconductor memory, or M8743 MS11-P.
Source: PDP-11/44 System User's Guide
Memory
Standard on this model was memory management and an 8KByte (KK11-B) cache. Memory addressing using 22 bits allowed a 4MByte maximum memory size. AS the memory addressing was 22 bits, not the 18 bits of the UNIBUS, the memory could not be resident on the UNIBUS. Instead a memory bus was added to the CPU (PAX Memory Bus) to access the 22 bit address space. This was similar to the subsequent approach used on the MicroVAX II where the CPU had access to a memory bus, separate from the QBus.
Commercial Instruction SetAn optional (KE44-A) Commercial Instruction Set (CIS) extension could be added by adding two boards (M7091, M7092) adjacent to the Console Interface Module. This option extends the instruction set of the PDP-11 with instructions optimized for commercial applications. By contrast, in the LSI-11/03, due to VLSI, this was a single 40-pin DIP chip instead of the two cards on this processor.
Console ModeIn "console mode" the user can enter console specific commands through a terminal. When not in console mode, the user can interact with the operating system or programs running on the PDP-11. To enter console mode, the user would type "control P". The key switch must be in the LOCAL position to enter console mode. The programmer's console switch only had three positions:
- BOOT - press to enable enable the boot program.
- CONT - Continue the CPU program.
- HALT - Stop the CPU program.
Source: pdp-11.nl
PDP-11/44 Guides
| Document Name | Order Part No. | Publication Date | Domain |
|---|---|---|---|
| PDP-11/44 System User's Guide | EK-11044-UG-003 | July 1981 | USR |
| PDP-11/44 System Technical Manual | EK-KD11Z-TM-001 | December 1980 | HW |
| PDP-11/44 Field Maintenance Print Set | MP00897 | November 1979 | HW |
- Adapted from: Gunkies.org