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Re: Undocumented 6502 Opcodes (HCF) [message #113831] Tue, 17 September 2013 14:47
darrelj is currently offline  darrelj
Messages: 37
Registered: February 2013
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Message-ID: <1788@sdcrdcf.UUCP>
Date: Tue, 26-Feb-85 11:41:42 EST
Article-I.D.: sdcrdcf.1788
Posted: Tue Feb 26 11:41:42 1985
Date-Received: Fri, 1-Mar-85 20:15:10 EST
References: <376@aicchi.UUCP> <74@cvl.UUCP>
Reply-To: darrelj@sdcrdcf.UUCP (Darrel VanBuer)
Distribution: net
Organization: System Development Corp. R+D, Santa Monica
Lines: 17
Summary: 

Opcodes like HCF (halt and catch fire) go back far farther than the 6502.
I've seen this on lists of bogus op codes 15 years ago and were old then.
The majority of them date from the days of the first mass produced computers
(i.e. hundreds rather than a few hand-built copies) where assembler was the
only way and the machines were full of ideosyncrasies in efficient
operation--like the 1401 which had an opcode to read a card, punch a card
and print a line simultaneously, in part because the machine had no
interrupts.
-- 
Darrel J. Van Buer, PhD
System Development Corp.
2500 Colorado Ave
Santa Monica, CA 90406
(213)820-4111 x5449
...{allegra,burdvax,cbosgd,hplabs,ihnp4,orstcs,sdcsvax,ucla-cs,akgua}
                                                            !sdcrdcf!darrelj
VANBUER@USC-ECL.ARPA
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