17 Sep
2015
17 Sep
'15
10:33 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Jon Elson
Sent: 17 September 2015 17:44
To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic and Off-
Topic Posts <cctalk at classiccmp.org>
Subject: Re: ENIAC programming Was: release dates of early microcomputer
operating systems, incl. Intel ISIS
Most modern computer languages run with the executable instructions in a
"pure code" section, which is set to be NOT writeable by the program.
This
From:
Dave Wade
to me a "computer" without
self-modifying code is a programmable
calculator even if it has index registers...
avoids a LOT of simple mistakes and REALLY hard to
find program crashes.
This is true of MS, Linux/Unix and the VMS program environment that I have
used for about 40 years. I think you have to go back to maybe Windows 95
or
RT-11 to not have that protection.
Windows/ME was the last program not to have that protection, but it is just
that, protection. At certain points in the execution process masks are set
to prevent programs from modifying themselves, at a macro level the system
has the capability to modify instructions, in the general case if the system
is considered a program, then it applies protections to prevent subsets of
code doing this....
Jon