Game Analysis on Programming the Atari VCS in Assembly

Pong (a minimal teardown)

Mon, 01 Jan 0001 00:00:00 +0000

Pong (a minimal teardown)#

Where Combat and Pitfall! are feats of compression — huge games squeezed into tiny ROMs — this Pong is the opposite lesson: the irreducible minimum, the smallest thing that is still a complete VCS game. It’s a clean, modern implementation by Lucas Avanço, built on Kirk Israel’s “thin red line” tutorial and the Stella Programmer’s Guide — not Atari’s 1977 cartridge, but all the better for reading, because there’s nothing in it that isn’t essential.

Combat (1977)

Mon, 01 Jan 0001 00:00:00 +0000

Combat (1977)#

Combat shipped in the box with the original console — for millions of people it was the Atari. Written by Larry Wagner with hardware help from Joe DeCuir, it packs 27 game variations (tanks, tank-pong, invisible tanks, biplanes, jets) into a 2 KB ROM. It’s also one of the most thoroughly annotated programs in 2600 history: the commented disassembly this teardown follows runs from Harry Dodgson’s original through Nick Bensema’s notes (1997) to Roger Williams’ full overhaul (2002).

Pitfall! (1982)

Mon, 01 Jan 0001 00:00:00 +0000

Pitfall! (1982)#

Pitfall! — David Crane, Activision, 1982 — sent Pitfall Harry running through a 255-room jungle of logs, vines, crocodiles, scorpions, and quicksand, and became one of the best-selling games on the system. It did all that on a 4 KB cartridge, which raises an obvious question: where do 255 rooms fit? The answer is the most famous idea in 2600 programming, and it’s the reason this game is worth taking apart. (The disassembly here is Thomas Jentzsch’s.)

Adventure (1980)

Mon, 01 Jan 0001 00:00:00 +0000

Adventure (1980)#

Adventure — Warren Robinett, Atari — put an entire explorable world on the console: roughly thirty connected rooms, items you carry one at a time, three dragons that hunt you, a thieving bat, and locked castles opened with keys. It was the first action-adventure game on a home console, packing an astonishingly rich world into a 4 KB cartridge. It’s also famous for its hidden “Created by Warren Robinett” room — widely regarded as the first famous Easter egg in a video game, and the one that popularized the tradition of hiding secrets for players to find.

River Raid (1982)

Mon, 01 Jan 0001 00:00:00 +0000

River Raid (1982)#

River Raid — Carol Shaw, Activision — flies a jet up a winding river that never ends: shoot the ships, helicopters, and jets, blow the bridges, and watch the fuel gauge, because the banks keep narrowing. It was one of the best-selling and most acclaimed games of the era, and a landmark for another reason — Shaw was among the first women to design and program a commercial video game, and River Raid is her masterpiece. The disassembly here is Thomas Jentzsch’s.

Space Invaders (1980)

Mon, 01 Jan 0001 00:00:00 +0000

Space Invaders (1980)#

Space Invaders — Rick Maurer, Atari — was the first officially licensed arcade game to land on a home console, and it changed everything. It was the 2600’s killer app: the cartridge people bought the console in order to play, widely credited with roughly quadrupling hardware sales in 1980 and turning the VCS from a curiosity into a phenomenon. Maurer’s port is also a quiet masterclass in TIA economy — it fills the screen with marching aliens using astonishingly little hardware. The disassembly here was produced from the cartridge with DiStella.

Video Chess (1979)

Mon, 01 Jan 0001 00:00:00 +0000

Video Chess (1979)#

Video Chess — Larry Wagner (the chess engine) and Bob Whitehead (the kernel and display), Atari — is the one that shouldn’t fit. It is a real chess program: it knows the legal moves, it looks ahead, it plays a whole game against you at eight levels of strength. And it does all of that in 4 KB of ROM and 128 bytes of RAM — less working memory than a single line of this paragraph. By legend it almost didn’t ship: Atari had advertised a chess cartridge in its earliest VCS catalog, couldn’t deliver for a year or two, and — the often-told story goes — a customer’s threatened lawsuit over the no-show product is what finally pushed it out the door in 1979.

Cosmic Ark (1982)

Mon, 01 Jan 0001 00:00:00 +0000

Cosmic Ark (1982)#

Cosmic Ark — Rob Fulop, Imagic — casts you as a sort of Noah in orbit: a great ark sweeping the galaxy to rescue pairs of animals from dying worlds. It plays in two alternating acts — fend off a meteor storm from the center of the screen, then drop to a planet and lift creatures aboard with a tractor beam. It’s a fine game. But it is remembered for four instructions.

Breakout (1978)

Mon, 01 Jan 0001 00:00:00 +0000

Breakout (1978)#

Breakout is where the VCS came from. The 1976 arcade machine was conceived by Nolan Bushnell and Steve Bristow as a one-player Pong with a wall to chip away at, and the prototype was built — famously, over a few sleepless nights — by Steve Wozniak, with Steve Jobs handling the deal with Atari (and, the story goes, the bonus). The 1978 cartridge brought it home. It is Pong’s child: a ball, a paddle, and a wall of bricks.