[TUHS] v6 RK05 bootloader question

John Cowan 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

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