[TUHS] v6 RK05 bootloader question
cowan at mercury.ccil.org
Thu Dec 31 04:33:31 AEST 2015
Erik E. Fair scripsit:
> Rather than memory-mapped I/O, the NOVA had I/O instructions, and
> six bits of device codes.
Same as the PDP-8, in fact. But all my PDP-8 work was with OS/8,
which runs with interrupts off: you can turn them on in userland if your
program wants to use them, but you have to shut them off before invoking
any system services. So I know little of these sixties sitcoms of
which you speak.
> Since "page zero" of the NOVA (the first 256 words of RAM) was a
> critical resource (direct reference from anywhere else in RAM rather
> than using space-expensive indirect addressing, plus, there were some
> autoincrement and autodecrement locations - reading them caused the
> stored value to change - handy for counters and pointers),
All exactly like the PDP-8.
John Cowan http://www.ccil.org/~cowan cowan at ccil.org
You are a child of the universe no less than the trees and all other acyclic
graphs; you have a right to be here. --DeXiderata by Sean McGrath
More information about the TUHS