Programming the Stella "1D" Atari 2600 Graphics Chip

[quadz]

Greetings and Salutations,

A fun article on programming the "Stella" graphics chip
on the old Atari 2600 game system.  It's actually a "1D"
graphics chip!  Every scan line will be an exact duplicate
of the previous scan line, unless the CPU changes the bits
in the playfield or sprite registers before the video beam
draws those pixels.

http://www.kuro5hin.org/story/2001/9/15/211737/858

Now I finally understand why those old 2600 games looked
the way they did. . . . And it lends a newfound sense of
respect for games like Pitfall that had above average
graphics for the time.




Regards,

quadz

[quadz]

P.S. detailed Stella proramming manual at: http://atarihq.com/danb/files/stella.pdf


Wow, after reading that... what a pain in the ass!!!   

[reaper]

amazing how much of a challenge it was back then to get something done, and then they have to worry about the limited resources.

[quadz]

and then they have to worry about the limited resources.

Indeed:

CPU: 1.19Mhz
RAM: 128 bytes
ROM: 4K Cartridge ROM space

[zndkw1n]

And such classics were brought to us by this great 2600 system, like ET.   

[quadz]

In 2012, a programmer re-implemented Pac Man for Atari 2600, from scratch, constrained to the same 4K specs that crippled the original in 1982.

Dunno how many folks recall how controversial the official Atari 2600 Pac Man was?


http://www.youtube.com/watch?v=HL2p2ANFlQ4  <- original 2600 mess

Granted, the 1D stella gfx chip was exceedingly difficult to program.

But, I'll likely never forget how disappointed me and my 4th and 5th grade neighborhood buddies were after all the excitement leading up to its release in 1982.

Since then I've occasionally wondered how much further the hardware could have been pushed by a different programmer. Lo and behold, someone's recently implemented a from-scratch pac man version on a 2600 emulator, restricted to the same 4K cartridge specs as the original:


http://www.youtube.com/watch?v=dAYuBcuvIww  <- 2012 homebrew (same 4K spec as original)

Improvements over Atari's 1982 Pac-Man:

- Original, arcade maze layout
- Proper "siren" sound that changes pitch
- Monsters are proper colors
- Maze is correct colors
- Pac-Man and Ghost graphics much truer to arcade
- Monster behavior modeled after arcade
- Bonus items true to arcade

man... we'd have indeed been some happy munchkins in 1982 if this had been the cartridge that shipped at that time!

The amazing thing, of course, being it could have been