[Simh] Porting simh for IBM VM/CMS

[rubhone at aol.com]

I have made substantial progress in an attempt to run simh under IBM's VM/370 CMS environment.


Difficulties include:
	lack of a proper "make" facility
	external reference and symbolic names limited to 8 characters
	no hierarchical file system
	OS dependencies for file I/O, timers, etc.
	file system preference for fixed length 80 byte record-oriented files
		makes importing source code awkward


Despite all of this, I am currently able to compile, load and execute the simh scp for a
target ALTAIR system.   Console interactions (set/show) are fine, and the sim will run
"do" files upon startup and interactively.


I am currently trying to get the "attach <dev> <file>" code working.  This made me realize
that a compiler (gcc) warning regarding sim_switches and SWMASK is a real issue.


The EBCDIC character set used on IBM systems has gaps in the codes for "A" to "Z",
occupying an integer range of 41 values.  This causes the left shift in SWMASK to exceed
the defined size of int32 for sim_switches.


My broad range of old-school programming by no means makes me an expert in C.
Any ideas on a compact solution for this character set problem?


Regards,
Fritz




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