AUTHOR'S PREFACE



     during the VBLANK interval, causing the computer to jump to a
     user-specified location to process a short user-written routine
     during the VBLANK process.

VBLANK:	Vertical Blank. The interval between the time the TV
     electron beam turns off after reaching the bottom right corner of
     the screen and returns to the top left corner and turns back on
     again. This small time period may be used by machine language
     programmers for short routines without interrupting the display
     by writing a VBI (above). There are two VBLANK stages. Stage
     one is performed every VBLANK cycle (1/60 second). Stage two
     is performed either every 1/30 second or every 1/60 second when
     it doesn't interrupt time-critical code being executed. See the
     end of the memory map for the processes executed in each stage.

SOURCES
Letters in brackets are used in this guide to identify the source.

(*M) Master Memory Map Ver. 2, Santa Cruz Educational Software,
1981. A memory guide by the same people who brought us the
TRICKY TUTORIAL series. The latter are both tutorials and
applications utilities. The map does contain some annoying errata.

(*Y) Your Atari Computer, by Lon Poole with Martin McNiff & Steven
Cook, Osborne/McGraw-Hill, 1982. The best guide to date on general
use of the Atari. Very highly recommended

(*C) COMPUTE!'s First Book of Atari, by the Editors of COMPUTE!
Magazine, Small System Services Inc., 1981. A good collection of
early articles that appeared in the magazine.
At the time of this writing, COMPUTE!'s Second Book of Atari had just
been released. It is therefore not used as a reference source here, but it
is a must for serious programmers. It contains a wealth of information
on an enormous range of topics, including advanced graphics, forced-
read modes, page flipping, Atari BASIC and many valuable utilities. It
should be a staple in most Atari owners' libraries.

(*I) Inside Atari DOS, compiled by Bill Wilkinson, published by
COMPUTE! Books, Small System Services, Inc., 1982. An
explanation and copyrighted source code for the FMS portion of DOS
2.0.

Atari BASIC: Learning by Using, by Thomas Rowley, Hofhacker
Press, 1981. A lot of information packed into a surprisingly good little
book.

The following publications are all from Atari, Inc. I recommend them
to all truly interested in understanding their Atari computers:

(*D): De Re Atari: an arcane, but indispensable reference to the
Atari's operations and come of its most impressive aspects, by Chris