Depends the processor. For the 11/45 class processors, you had a 17th
address bit, which was the I/D choice. For the 11/40 class you shared the
instructions and data space. So you had to use overlays and thunks at lot
sooner.
On Tue, Jan 6, 2015 at 2:57 PM, Milo Velimirović <milov(a)cs.uwlax.edu> wrote:
Bringing a conversation back online.
On Jan 6, 2015, at 6:22 AM, arnold(a)skeeve.com wrote:
Peter
Jeremy scripsit:
> But you pay for the size of $TERMCAP in every process you run.
John Cowan <cowan(a)mercury.ccil.org> wrote:
> A single termcap line doesn't cost that much, less than a KB in most
cases.
In 1981 terms, this has more weight. On a non-split I/D PDP-11 you only
have 32KB to start with. (The discussion a few weeks ago about cutting
yacc down to size comes to mind…)
(Or even earlier than ’81.) How did pdp11 UNIXes handle per process
memory? It’s suggested above that there was a 50-50 split of the 64KB
address space between instructions and data. My own recollection is that
you got any combination of instruction and data space that was <64KB. This
would also be subject to limits of pdp11 memory management unit.
Anyone have a definitive answer or pointer to appropriate man page or
source code?
Thanks,
Milo
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