Self modifying code, lambda calculus - Re: ENIAC programming

Chuck Guzis cclist at
Sun Sep 20 12:46:29 CDT 2015

On 09/20/2015 09:00 AM, Peter Coghlan wrote:

> CHAIN <filename> is roughly equivelant to LOAD <filename> followed by
> RUN. Unlike LOAD, CHAIN can be issued from a program so it can be
> used for a kind of overlay where one program is run and then replaced
> by another program when it completes.  However, like LOAD (and RUN),
> CHAIN also clears most variables so the amount of initialisation that
> can be done in the first program is quite limited.

Some BASICs implement a type of COMMON (to borrow from FORTRAN) which 
contains variables for communication between CHAINed program units.  In 
that respect, CHAINed programs behave much more like overlays, albeit 
all as level (0,0).   I'm not certain that any BASICs implement the 
FORTRAN-style overlay hierarchy.


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