PDP-11/04

PDP-11/04

There is a great page on the 11/04 right here: http://www.corestore.org/1104.htm

From the page:

The 11/04 was a mid/late-70s implementation of the Unibus pdp-11 architecture, and was essentially a replacement for the 11/05 & 11/10. It was the first pdp-11 to escape without a 'proper' lights & switches front panel, instead it had the glorified 'programmers console' as an option - a hex keypad and an LED display which showed address/data digitally.

It came in two chassis, like the 11/05 & 11/10 - a half-height example, which had the entire Unibus backplane, power supply, front panel - basically the whole computer - sliding into an evil jamming finger-trapping metal sleeve - and a full-height example, basically the same BA11 box as used by the 11/35 and many many other DEC applications. It's very similar to its higher-spec twin, the 11/34.

Registers

Like its predecessor PDP-11/05, the general registers (R0-R5, SP and PC) have addresses assigned to them, which makes them accessible from the KY11-LB Programmer's Console when the machine is halted. Their addresses are:

Address	Register
777700	R0
...
777705	R5
777706	SP
777707	PC

Note that the register addresses, like those on the 11/05, increment by 1, not by 2, as is usual for word-sized items.

In addition, four internal CPU registers which record the CPU's most recent memory operations are also available:

Address	Register
777710	Source address
777711	Source data
777712	Destination address
777713	Destination data