Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA Path: utzoo!watmath!clyde!cbosgd!cbdkc1!desoto!packard!edsel!bentley!hoxna!houxm!whuxlm!harpo!decvax!genrad!mit-eddie!godot!harvard!seismo!brl-tgr!tgr!ACB.TYM@OFFICE-2.ARPA 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!).