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From: rick@pavlov.ssctr.bcm.tmc.edu (Richard H. Miller)
Newsgroups: comp.arch
Subject: Re: PDP-10 (was: Looking for a really odd computer)
Message-ID: <2189@gazette.bcm.tmc.edu>
Date: 9 Oct 90 21:35:31 GMT
References: <2515@ns-mx.uiowa.edu> <71383@sgi.sgi.com> <1990Oct8.214604.25320@ns.network.com>
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In article <1990Oct8.214604.25320@ns.network.com> ddb@ns.network.com (David Dyer-Bennet) writes:
>In article <71383@sgi.sgi.com> rpw3@sgi.com (Rob Warnock) writes:
>[referring to the DEC PDP-10]
>:I don't recall any production software that used 9-bit bytes, though at least
>:one attempt at an experimental C compiler used them.
>
>I seem to recall that the COBOL compiler used them for some modes of
>character data or character numeric data.  Can't figure out why
>offhand, though.

Ah yes....DISPLAY-9. This was also known as EBCDIC. The COBOL compiler would generate IBM
compatible programs and would write a tape or read a tape which could be used on an IBM system
(32 bit word size, 4 bytes/word). DISPLAY-9 would store 4 characters in a word and when you 
wrote to the tape, would convert the 36 bit words to 32 bit frames on the tape. Once could
select DISPLAY-9 explicitly or one would get it automatically when an IBM recording mode was
selected on the FD statement in the data division. It actually worked fairly well, but the
programmer had to be very careful that his/her record sizes were an even multiple of both 6 
and 4. 
 

-- 
Richard H. Miller                 Email: rick@bcm.tmc.edu
Asst. Dir. for Technical Support  Voice: (713)798-3532
Baylor College of Medicine        US Mail: One Baylor Plaza, 302H
                                           Houston, Texas 77030