Questions tagged [pdp-8]
For questions regarding the DEC PDP-8 minicomputer.
4
votes
2answers
128 views
Does the Intersil 6100 do interrupts differently from other PDP-8s?
As I recall, the original PDP-8 actually does a jsr 0000 when an interrupt happens, so that the interrupt service routine started at address 0001. I think that saves a few gates, since the instruction ...
13
votes
3answers
2k views
Size of the PDP-8
What is the physical size of a PDP-8? The photographs I found seem to be evenly divided between showing it as a compact unit that looks maybe one foot high, and as a tall cabinet maybe five or six ...
9
votes
3answers
739 views
PDP-8 transistor count
https://en.wikipedia.org/wiki/Transistor_count provides some transistor count figures for early microprocessors, e.g. 8008 and 6502 both listed at around 3500.
The PDP-8 was a 12-bit computer with a ...
9
votes
3answers
1k views
How did the PDP-8 handle strings?
The PDP-8 was a popular 12-bit minicomputer of the late sixties. It used word addressing, so that it always dealt in 12-bit words, of which it could address 4096 with a full bank of core memory.
In ...
8
votes
3answers
418 views
Arithmetic operations on multiple words on the PDP-8
For the PDP-8 with its strange ISA, I've always wondered what the "standard" (i.e. fastest) way to do arithmetic operations (add, subtract, maybe multiply) on integers consisting of multiple words was....
15
votes
3answers
605 views
Conditional skip instructions of the PDP-8
I am interested in the SKIP instructions on the PDP-8. These test the accumulator and Link bit, and they skip the next instruction if the condition holds.
The instructions are:
OR GROUP
SMA - Skip ...
18
votes
3answers
918 views
Use of undocumented opcodes
I figure this is fitting for Retrocomputing.SE because CPUs like the 6502 and Z80 and the PDP-8, and probably others, have undocumented instructions and will happily execute them, in contrast with ...
