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Inter-Office 1Y1emoranduflI
To Cyprians Date January 29) 1976
From Tesler, Merry, Sproull,
Lampson, Ingalls location Palo Alto
Subject Font Format .Organization PARe
XERO)(.
This memo explains how we arrived at a font format that is twice as compact as .A L format and is
easy to use with l3itI3lt.
Backgroufl{}
Everybody who ever tried to make the Alto do graphics wondered why there was .no BitBlt, so now
there is one, and it is wonderful for moving rectangles around the screen, making gray boxes, and
painting. But some of us have been less than delighted with its use for "scan conversion of ll
characters. This has been a surprise, because we always thought of BitBlt as a way of making
character display easier.
The Tnh!enu Scheme
Our first idea long ago was to have something like the 8 character wide by 16 character high
Tableau of the Smalltalk font editor. a bitmap tiled with the characters of a font. \-Vith ascii 0
placed in the upper left corner, one can easily find the upper-left-origin source rectangle of any
character by:
source x = fontmaxwidth * (ascii & 7) <--
source