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From: demarem@clutx.clarkson.edu (Mike deMare (Anomoly Daemon),222 Hamlin,,2684041)
Newsgroups: misc.wanted,comp.sys.misc,comp.os.cpm,alt.folklore.computers
Subject: Re: Need info for an S-100 bus system
Message-ID: <1990Oct13.163615.6218@news.clarkson.edu>
Date: 13 Oct 90 16:36:15 GMT
References: <1990Oct12.235220.18522@techbook.com>
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From article <1990Oct12.235220.18522@techbook.com>, by fzsitvay@techbook.com (Frank Zsitvay):
> In article <1990Oct12.000849.12599@news.clarkson.edu> demarem@clutx.clarkson.edu writes:
>>I suspect that your choices for an OS are CP/M or CP/M :-).  You
>>can probably order documentation and/or CP/M drivers for your
>>devices, but you may have a bootstrap problem..you need the system
>>running CP/M in order to modify CP/M for the system.  One nice thing
>>about CP/M is that the BIOS sources (in assembler) come with it
>>so you ought to do okay.  I would recommend aquiring the following
>>items (to run on another system while getting your S-100 up):
>>
>>8080 cross-assembler
>   
>   An 8080 cross assembler on a cp/m machine??  go figure...
> 

I was thinking in terms of assembling some code on his "real" machine
and keying it in through the monitor or frontpanel (ugh).  I have seen
some nice 8080 assemblers running on PDP-11's (under Unix lev. 6).

>>Small-C (8080 version, source code is available, I have seen it in
>>         *very* old Doctor Dobbs Journals, and believe that some
>>	 user groups have it available in machine readable form).
>    NO!
> 
>    Don't do this!  Bad idea.
> 
>    you don't want to write a bios in c.   you're only restricted to
> a maximum address space of 64k, so your bios has to be as small and
> as fast as possible.  this is very important if you plan to add
> double density drives to the system, since that requires some form
> of sector blocking/deblocking.  you do that in c and the bios will
> be much larger than it needs to be.  the best tools to use when writing
> or hacking a bios is either ASM (which comes wth cpm) or RMAC, DR's
> relocating macro assembler.  the job is easier with RMAC because it 
> will generate your DPHs and DPBs for you.  My cpm mentor tells me MASM
> will not work for this.

Quite clearly you are correct, it is inappropriate to code a BIOS
in C.  But I had something a little different in mind..realating
to AFTER he got the system up.

> fzsitvay@techbook.COM - one of these days i'll get it right...
> 
> Version 2 of anything is usually the version that works.

Mike

Crime does not pay ... as well as politics.
		-- A. E. Newman