> -----Original Message----- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Jon Elson > Sent: 17 September 2015 17:44 > To: gene...@classiccmp.org; discuss...@classiccmp.org:On-Topic and Off- > Topic Posts <cctalk@classiccmp.org> > Subject: Re: ENIAC programming Was: release dates of early microcomputer > operating systems, incl. Intel ISIS > > > > > From: Dave Wade > > > > > > > > > to me a "computer" without self-modifying code is a programmable > > > calculator even if it has index registers... > > > > > 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 > 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
