MOST-POSITIVE-LIVEJOURNALLER-AGE

Mr. Jalopy discusses the meaning of a 1964 Ford Galaxie 500 rocket car.

JWZ gets prehistoric:

;;; -*- Mode:Lisp; Syntax: Common-Lisp; Package:USER; Base:10 -*-

;;; 21 Mar 90   Jamie Zawinski   Created.

;;; When you load this file, the constants MOST-POSITIVE-BIGNUM and
;;; MOST-NEGATIVE-BIGNUM will be defined.
;;;
;;; These are the absolute largest and smallest numbers which can be
;;; represented in the TI Explorer's memory architecture.
;;;
;;; WARNING: if you try to print these numbers, the microcode will
;;; hang.  They are totally useless quantities, and dangerous to
;;; have around.  You can examine them with 
;;; (sys:dump-memory most-positive-bignum :bignum-is-dump-object t)
;;; and perform normal arithmetic operations on them.  But the same
;;; dangers apply to any numbers this large.

For non-lispers: bignums aren't supposed to have limits, so just the name “MOST-POSITIVE-BIGNUM” will make Lispers laugh a little. In practice, a number with more than one million digits, that takes 3 days just to display on screen, doesn't seem like much of a limit.

The fact that adding 1 to MOST-POSITIVE-BIGNUM results in a piece of data whose value is 0 but takes up 524 KB of memory is just a bonus.

Posted by jjwiseman at March 26, 2008 01:56 PM