De Re Atari
Encyclopedia
De Re Atari written by Chris Crawford
in 1982 contains a detailed description of the advanced features of the Atari 8-bit family
of home computer
s. Atari's own technical documentation only became available to the public some time later, so for a good deal of the time that the machine was popular developers on the platform turned to De Re and Mapping the Atari
as crucial development aids.
After some basic introductory information, the book quickly gets "down to business". Individual chapters are devoted to making use of the features of the platform, which included ANTIC
and the display list
, "graphics indirection" in the form of color support in the GTIA
and customized character sets, player-missile graphics
, using display list interrupts (the VBI
and HBI
), smooth scrolling and sound, including a discussion of "volume only sound" which offered higher-resolution volume control for digitized sample playback. Additional chapters covered utilities in the operating system
, Atari DOS
and Atari BASIC
.
How to make use of these features was often not obvious. For instance, Atari's sprite implementation, player-missile graphics, used a register to indicate the
position of sprite on the screen, but required the user to copy the sprite pattern up or down in memory to move it along the 
axis. Likewise, vertical smooth scrolling was quite simple, but horizontal scrolling required a custom display list that created a "virtual screen" as wide as the scrolling playfield. De Re not only talked about these issues, but provided sample implementations and discussed potential alternate implementations.
Crawford had personally made use of many of these features in the seminal wargame
Eastern Front (1941) released the previous year. Eastern Front made extensive use of smooth scrolling, custom character graphics and some use of player-missile graphics and basic sound.
The original edition is now out-of-print but available for viewing on a site maintained by Kevin Savetz, the Atari Archives.
Chris Crawford (game designer)
Christopher Crawford is a computer game designer and writer noted for creating a number of important games in the 1980s, founding The Journal of Computer Game Design, and organizing the Computer Game Developers' Conference.- Biography :...
in 1982 contains a detailed description of the advanced features of the Atari 8-bit family
Atari 8-bit family
The Atari 8-bit family is a series of 8-bit home computers manufactured from 1979 to 1992. All are based on the MOS Technology 6502 CPU and were the first home computers designed with custom coprocessor chips...
of home computer
Home computer
Home computers were a class of microcomputers entering the market in 1977, and becoming increasingly common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single nontechnical user...
s. Atari's own technical documentation only became available to the public some time later, so for a good deal of the time that the machine was popular developers on the platform turned to De Re and Mapping the Atari
Mapping the Atari
Mapping the Atari, written by Ian Chadwick in 1983, is a location-by-location explanation of the Atari 8-bit family's memory map. It was one of the "must have" references for programming the platform, although it was published somewhat late in the machine's timeline...
as crucial development aids.
After some basic introductory information, the book quickly gets "down to business". Individual chapters are devoted to making use of the features of the platform, which included ANTIC
ANTIC
Alphanumeric Television Interface Controller is an early video system chip used in the Atari 8-bit family of microcomputers as well as the Atari 5200 in the 1980s. The chip was patented by Atari, Inc. in 1981...
and the display list
Display list
A display list is a series of graphics commands that define an output image. The image is created by executing the commands....
, "graphics indirection" in the form of color support in the GTIA
George's Television Interface Adapter
Color Television Interface Adaptor and its successor Graphic Television Interface Adaptor are custom chips used in the Atari 8-bit family of computers and in the Atari 5200 console. In these systems, a CTIA or GTIA chip works together with ANTIC to produce video display...
and customized character sets, player-missile graphics
Sprite (computer graphics)
In computer graphics, a sprite is a two-dimensional image or animation that is integrated into a larger scene...
, using display list interrupts (the VBI
Vertical blank interrupt
A vertical blank interrupt is a programming technique used in some systems, notably video games and consoles, to allow program code to be run in the periods when the display hardware is turned off, waiting for the TV to complete its vertical blank.Since the vertical blank period occurs at the...
and HBI
Horizontal blank interrupt
A horizontal blank interrupt is a programming technique used in some systems, notably video games and consoles, to allow program code to be run in the periods when the display hardware is turned off, waiting for the TV to complete its horizontal blank, which takes about 10 μS.The technique was only...
), smooth scrolling and sound, including a discussion of "volume only sound" which offered higher-resolution volume control for digitized sample playback. Additional chapters covered utilities in the operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
, Atari DOS
Atari DOS
Atari DOS is the disk operating system used with the Atari 8-bit family of computers. Operating system extensions loaded into memory were required in order for an Atari computer to access a disk drive. These extensions to the operating system added the disk handler and other file management...
and Atari BASIC
Atari BASIC
Atari BASIC is a BASIC interpreter for the Atari 8-bit family of 6502-based home computers. The interpreter originally shipped on an 8 KB cartridge; on later XL/XE model computers it was built in, with an option to disable it, and started when the machines were booted with no other cartridges...
.
How to make use of these features was often not obvious. For instance, Atari's sprite implementation, player-missile graphics, used a register to indicate the
position of sprite on the screen, but required the user to copy the sprite pattern up or down in memory to move it along the axis. Likewise, vertical smooth scrolling was quite simple, but horizontal scrolling required a custom display list that created a "virtual screen" as wide as the scrolling playfield. De Re not only talked about these issues, but provided sample implementations and discussed potential alternate implementations.Crawford had personally made use of many of these features in the seminal wargame
Wargame (video games)
Wargames are a subgenre of strategy video games that emphasize strategic or tactical warfare on a map, as well as historical accuracy.-History:The genre of wargame video games is derived from earlier forms of wargames...
Eastern Front (1941) released the previous year. Eastern Front made extensive use of smooth scrolling, custom character graphics and some use of player-missile graphics and basic sound.
The original edition is now out-of-print but available for viewing on a site maintained by Kevin Savetz, the Atari Archives.