🚀 go-pugleaf

In article <11212.664...@mts.rpi.edu> Greg_d...@mts.rpi.edu (Commander Krugannal) writes:
>
>     One program segment I have never tried, but supposedly works
>   on at least the IBM 3081D, is the statement BALR 12,12.
>   This instructs the assember to branch to 12 and load the value
>   of 12 and exucute it. 

Nope, this isn't BALR at all. You might have had an interesting
program, but this isn't it....

>     Well, the command 12 is BALR, so this 
>   essentially tells itself to BALR to itself, and excute what is
>   there, which is a BALR and you get the picture. :-)

I don't see what this has to do with my original posting on the
topic of "revenge" anyway..

Along a similar line, though, is the execute instruction, which
IS a command to execute the target instruction "out of line".
Apparently on the 709x series of computers, the single instruction
sequence XEC * (execute this instruction) caused the CPU to get
stuck in the fetch part of the instruction cycle (it never quite
succeeded at obtaining the instruction that was to be done).

The console STOP key was only polled after the completion of an
instruction cycle, so was of no effect during XEC * processing.
It was necessary to power off the machine to break the loop.
Subsequent IBM machines which had an execute instruction also
had an interrupt (program exception) if the execute target was
itself an execute op. I guess they learned something along the
way   :-)

Michael Stimac
.....sun!oliveb!tymix!stimac