🚀 go-pugleaf

Hello!

Among the few MS-DOS programs that will run on a 80386, but not on
an i486 based machine, there's a program called "PC Scheme"
by Texas Instruments (Scheme is a Lisp-like language). 

According to rumors, this is a result of the program changing 
some instructions in its own code-segment at runtime. 

-How can this cause incompatibilities between 
 80386 and i486 processors?
-I don't think every  self-modification of a program will
 cause problems. Exactly under what conditions may 
 problems occur? 
-Is there a way to detect this kind of self-modification
 either at runtime (say, with a small TSR debugger-like program) or 
 scanning the assembly-code sources.
-Are there any other mayor causes for i486 incompatibilities?

The source code of PC Scheme is available by FTP, so those interested
in this phenomenon can study it in detail:  
altdorf.ai.mit.edu 
in the directory /archive/pc-scheme/

Thanks in advance

Heinz-Bernd Eggenstein
CS, U. of Dortmund, FRG
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