Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wasatch!cs.utexas.edu!sm.unisys.com!ism780c!news
From: news@ism780c.isc.com (News system)
Newsgroups: comp.arch
Subject: Re: String lengths
Message-ID: <22196@ism780c.isc.com>
Date: 11 Feb 89 02:32:16 GMT
References: <8882@alice.UUCP> <22036@ism780c.isc.com> <1185@houxs.ATT.COM>
Reply-To: marv@ism780.UUCP (Marvin Rubenstein)
Organization: Interactive Systems Corp., Santa Monica CA
Lines: 20

[M Rubinstein]
>> The 7090 provided no instructions for accessing individual characters.

[J BEYER]
>This may be quibbling, but did not the Convert By Replacement From MQ
>and similar instructions deal with 6-bit characters on the 7090? I know
>they were not in the 704. Perhaps they did not get there until the 7094.
>But they were not full-fledged character manipulation primitives, I agree.
>It has been at least 20 years since I programmed one of those.

[M Rubinstein]
J BEYER is right about convert instructions on the 709/7090/7094 operating on
6 bit fields.  However the fields accessed were fields in a register.  The
were were no instructions for accessing 6 bit fields from memory.  There were
instructions for accessing two 15 bit fields from memory.  The fields were
called the address and decrment.  It is my understanding the the Lisp names
CAR and CDR come from the 15 bit field names.  CAR==contents of address
register, and CDR==contents of decrement register.

   Marv Rubinstein