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From: ACB.TYM@OFFICE-2.ARPA
Newsgroups: net.micro.cpm
Subject: Technical trivia
Message-ID: <6720@brl-tgr.ARPA>
Date: Fri, 21-Dec-84 11:20:48 EST
Article-I.D.: brl-tgr.6720
Posted: Fri Dec 21 11:20:48 1984
Date-Received: Sun, 23-Dec-84 00:38:33 EST
Sender: news@brl-tgr.ARPA
Organization: Ballistic Research Lab
Lines: 12

(everybody else puts a dummy line here. Why not?)

Speaking of technical data! I just spent most of a day discovering that BDS C 
uses the interrupt vector at location x'30' (RST 6).  I have often thought of 
using RST instructions for linkages in self relocating code BUT... I fear the 
impact on some unsuspecting user with some hardware interrupt configuration or 
some special storage locations (Some code uses the high end of interrupt vector
7 (DDT's RST location) already.  I read both CP/M documentation and BDS C 
documentation and find that in the CP/M documentation RST 6 locations are 
reserved and RST 7 is used by DDT.  I was a tad surprised to find that BDS C 
used RST 6.  Of course that is because I was using it (caught in the act!) 
although the use was unintentional (a bug!).