[inforoots] bits again

[Michael Albaugh]

On 11/28/06, Ed Thelen <ed at ed-thelen.org> wrote:

> A more appropriate question might be:
>
>    What machine was the first to *not* require self modifying code?
>    that is, a more convenient way to index?  - say using a "B-Box" ;-))
>                   and set up a subroutine return? - say a stack

I believe that the ability to execute an instruction from a register
pre-dates the B-Box, but could be wrong. Also, subroutine linkage
by way of a single "return address" or "return jump" location pre-dates
the use of a stack for that purpose. Our own 1401 has the interesting
optional feature that _any_ transfer of control can be a subroutine
jump. It is the first instruction at the call site that has the opportunity
to save the "return address", not a specific "call" instruction used by
the caller. Many ways to accomplish these goals.

  Mike