From:	bmorgan AT sdcc3 DOT ucsd DOT edu (Brent Morgan)
Newsgroups:	comp.os.msdos.djgpp
Subject:	how to address memory mapped DSP card using DJGPP
Date:	28 Nov 1996 22:46:29 GMT
Organization:	University of California, San Diego
Lines:	19
Message-ID:	<57l4o5$cm4@sdcc12.ucsd.edu>
NNTP-Posting-Host:	sdcc3.ucsd.edu
Keywords:	djgpp, memory mapped, dsp
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

I have an old DSP card (TMS320C25 based) that I'd like to use
under DOS, and address with a program written in C, compiled with
DJGPP.  I'm fairly ignorant of how my PC sees the dual-ported ram.
According to the manual I can set its initial address to a range
A000 to D000.  It uses 8k bytes following this initial address.  Are
there any references or caveats to using memory mapped cards under
DJGPP?  Does dual-ported in the case of this card refer to the fact
that both the PC and the DSP have this memory in their address
space? (Recent discussions about the new types of ram coming out 
seem to indicate that dual ported means that one can simultaneously
read and write.)  I don't see any chips on the card that look like ram
- is the memory-mapped address space mapped into the on-chip ram of the
DSP, or is it separate?  Any pointers would be appreciated.

Thanks in advance for your replies.
-- 
Brent A. Morgan

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