PDP-8/A

PDP-8/A
Year Introduced:	1976
Form Factor:	minicomputer
Word Size:	12
Logic Type:	TTL
Clock Speed:	333KHz
Memory Speed:	1.5 µseconds
Physical Address Size:	32KW (requires optional KM8-A)
Virtual Address Size:	4KW
Memory Management:	bank selection, CPU mode
Bus Architecture:	OMNIBUS
Operating System:	OS/8, TSS/8
Predecessor(s):	PDP-8/E

The PDP-8/A was DEC's last non-microprocessor PDP-8. The KK8-A CPU was a single hex board, which plugged into an OMNIBUS backplane. It supported both core main memory (MM8-AA and MM8-AB) and semiconductor (MS8-A).

There were a number of options available for use with the -8/A, including:

• KM8-A Extended Option - main memory extension and time-sharing control, etc
• FPP8/A Floating Point Processor
• DKC8-AA - front panel control, real-time clock, asynchronous serial line interface, etc

The FPP8/A used two hex boards; it was not part of the CPU, but used DMA for its instructions and data. Its floating point format provided three and six word formats, with 12 bits of exponent; it also supported double-word integers.

The -8/A could use either an Operator's Panel, or a Programmer's Panel (similar to the KY11-LB); the latter required the DKC8-AA.

The -8/A came either as a kit of boards, or as a complete system including a chassis, power supply and backplane; in the latter form, there was a list of different configurations.