Immutability - was Re: ENIAC programming Was: release dates of early microcomputer operating systems, incl. Intel ISIS

Toby Thain toby at
Thu Sep 17 12:29:34 CDT 2015

On 2015-09-17 12:44 PM, Jon Elson wrote:
>>      > 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.

Modern languages extend this "protection" further, to the programmer 
model, with immutable bindings and data structures, shunning variables 


> Jon

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