Subject: Re: Car and cdr (Re: Python syntax in Lisp and Scheme)
From: (Rob Warnock)
Date: Tue, 21 Oct 2003 01:52:07 -0500
Newsgroups: comp.lang.python,comp.lang.lisp
Message-ID: <>
Christos "TZOTZIOY" Georgiou  <> wrote:
| AFAIK car stands for contents of address register and
| cdr for contents of contents of data register.

From the IBM 704 CPU instruction format:
CAR == "Contents of Address [part of] Register".
CDR == "Contents of Decrement [part of] Register".
See <URL:>.

instructions used a similar format, but with the "decrement" part
being a negative count in the upper half of the word (which was
*incremented* in parallel with the address in the lower half
[or in the case of POP & POPJ only, decremented in parallel with
the address]).


Rob Warnock			<>
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