Old Atari Design Docs Online

gribbly writes "Forget emulation -- now you can read classic Atari design docs!" It's all documents from the early 1980s, I think, and looks totally...I dunno. It's like taking a journey into the past.

Comments

Re:Feature priorities askew?

[Olivier Galibert]

The video subsystems were completely different for computers than for arcade machines at this time[1].

Computers:
- framebuffer
- hardware support for scrolling of the pixels
- blitters
- hblank interrupt for effects

Arcade games:
- n planes of tile oriented video (i.e, the screen is divided into 8x8 elements selected by number)
- sprites generator (usually a plane of its own)
- priority manager
- hardware support for global scrolling of the tile planes
- horizontal and vertical line scrolling
- vblank interrupt only

There were numerous variants, of course, and some games used a framebuffer (williams games, mostly), but this is the usual architecture. It trades off genericity (you can't really draw a line in a no-framebuffer, tile-based system) for efficiency (zero-cpu-cost layers, independant busses for the graphic roms which are directly connected to the tile/sprites ICs, etc....). That's mostly what made them so impressive compared to the quite feeble CPUs they were using.

OG, mamedev

[1] Now everything has been unified under a common 3d-oriented architecture.