Re: Why I've Dropped In

On Fri, 13 Jun 2025 18:11:18 +0000, Thomas Koenig wrote:

Stephen Fuld <sfuld@alumni.cmu.edu.invalid> schrieb:
>

Even with that provision, it would not have worked.

>
All I can say is that it worked in several other contemporaneous
architectures.  Scott gave one example, the Burroughs Medium systems.
The Univac 1108 and followons is another.  There may be others, perhaps
the some of CDC systems as they and the Univac systems shared a common
designer (Seymour Cray).

>
The problem of the /360 was that they put their base registers in
user space.

A base register not part of GPRs is a descriptor (or segment).
And we don't want to go there.

            The other machines made it invisible from user space
and added its contents to every memory access.  This does not take
up opcode space and allows swapping in and out of the whole process,

It also fails when one has 137 different things to track with those
descriptors.

which was a much better solution for the early 1960s. (Actually, I
believe the UNIVAC had two, one for program and one for data).

Still insufficient for modern use cases.