From mboxrd@z Thu Jan  1 00:00:00 1970
From: cowan@mercury.ccil.org (John Cowan)
Date: Wed, 30 Dec 2015 13:33:31 -0500
Subject: [TUHS] v6 RK05 bootloader question
In-Reply-To: <22302.1451498817@cesium.clock.org>
References: <685C2CB4-B23B-4A9C-833D-EE27B37B7ECF@mailbox.org>
 <22302.1451498817@cesium.clock.org>
Message-ID: <20151230183331.GA448@mercury.ccil.org>

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