29 May
2014
29 May
'14
1:12 a.m.
-----Oorspronkelijk bericht-----
From: Chuck Guzis
Sent: Wednesday, May 28, 2014 10:42 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Catch and Halt Fire - Drama set in early days of personal
computing
On 05/28/2014 12:50 PM, Henk wrote:
Long ago, I worked on SPERRY 1100 systems (1100/63 and
1100/72), and
was one of the very few people allowed to program MASM. Makes sense,
as I was one of the two EXEC experts (I could read the panic dump and
find out why the system crashed). As said, long ago ...
I remember the EX (execute remote) instruction. I wonder what would
happen if you EX to another EX instruction that EX'd the first EX. That
would cause a loop, I guess. But both systems that I worked on, the
system would not hang, just the CPU executing the EX code.
I seem to recall that the S/360 had a special exception code for an EX
instruction being the object of another EX instruction.
--Chuck
I have no access to SPERRY documentation, but I would expect
that the 1100 also would recognize EX targeting an other EX and
generate an exception or trap. IIRC the word is 'contingency' in the
1100 jargon for 'exception'. End 80's memory cells starts to fail ...
- Henk