How a basement hacker transformed Donkey Kong for the Atari 2600

The following excerpt comes from Arcade Perfect: How Pac-Man, Mortal Kombat, and Other Coin-Op Classics Invaded the Living Room by David L. Craddock.

Sickly green light washed over the stubble and pale complexion of the man hunched in front of his computer monitor. Beside it sat a television, black except for five horizontal, crimson-colored bands running from top to bottom like lines on notebook paper.

Garry Kitchen closed his eyes, but the straight red lines were burned into the backs of his eyelids. Behind him came a steady pounding: pound—pound-pound-pound. He didnt rise to the bait. He knew what hed see. On the arcade cabinets screen, a giant ape the size of King Kong had just scaled a construction site made of straight red girders. With every stomp, the platforms had twisted and bent until they were slanted like ramps. Standing tall at the top, the ape intoned his grating, mechanical laugh.

Kitchen gritted his teeth. His replica of the construction site was almost perfect. Steel girders, a flaming barrel, a little man in red-and-blue overalls, an ape at the top.

There was just one glaring, maddening difference. His platforms refused to bend. That was going to be a problem.

Garry Kitchen watched the success of Mattels electronic games with interest. Just a few years ago hed been a college kid chasing an art degree and working part-time at Wickstead Design Associates, a firm that built consumer products like calculators and other digital electronics.

“I ended up getting involved in microprocessor engineering because I kind of had to,” Kitchen recalled. “During this time period, I'd switched from art in school to electrical engineering. I was learning engineering on the job, so why not finish my degree in engineering? We were a small company, I got dragged into doing work of a much higher caliber out of necessity. There was one guy who could, but he wasn't available.”

By 1978, consumer electronics were evolving from handheld electronics to Ataris 2600 machine. While Atari had started out as the sole manufacturer of games for its console, Activision opened that December and developed games for personal computers and the 2600—a tacit admission to developers everywhere that anyone could write games for Atari hardware. Kitchen went to his bosses at Wickstead Design Associates and made his case.

“Look, electronic toys are being hurt in the marketplace by video games,” he said. They stared blankly. Video games? Kitchen pressed on: “Everybodys jumping on this Atari thing. We should look into it.”

Kitchen asked around and received little feedback. Atari couldnt stop Activision and other studios from making games for its device, but it didnt have to help. There was no software development kit, no prototype console designed to write and test code. Activisions founders only knew how to make games for the 2600 because theyd worked with it while at the company.

By that time, Kitchen had flipped his schedule, working at WDA full-time and taking engineering classes at night. He wasnt making much money, pulling in $11,000 a year, but he enjoyed waking up every morning to solve new problems. Developing games for the 2600 was his latest and greatest challenge. Kitchen scraped together $1200 for an Apple II—the most expensive of 1977s “holy trinity” of personal computers, including the Commodore PET and Radio Shack TRS-80—and dissected his new machine to learn its ins and outs. It ran on a 6502 8-bit processor, which he picked up on quickly having worked with microprocessors on electronic toys.

Once he wrote code, he knew hed have to find a way to put it on an Atari 2600 cartridge. His solution was a custom-made board with a chip hed soldered on to play Atari ROMs. Testing code required him to run a ribbon cable from the chip on his board to the teeth in the 2600s cartridge slot.

Six months later, hed completely reverse-engineered the 2600 using his jerry-rigged setup and written a game, Space Jockey. The program weighed in at two kilobytes, four times the size of Mark Lessers 511-byte handheld games, and was much more complex. A shooter, Space Jockey scrolled the screen to the right as the player shot down enemy ships. Kitchen took his creation to his bosses at WDA. He had daydreamed about Atari and Activision getting into a bidding war over Space Jockey, one of the first Atari games written outside either studios walled garden. Instead, Donald Yu, one of his bosses, published it through US Games, a separate entity theyd founded to publish electronic toys. Yu licensed Space Jockey to his company and prepared to put it on the market.

Before, when Atari had employed the only engineers capable of writing software for its console, games had appeared at a steady drip. The advent of Activision and engineers such as Kitchen increased the drip to a steady flow. Consumers, thirsty for new titles, lapped them up, but Garry Kitchen wouldnt see a penny from any sales of Space Jockey when it released. His bosses, as the games publisher, would reap any rewards.

“You know,” he said to Yu and the others, “I should be making more money than $11,000.” Bankshot and Space Jockey had become two of WDAs biggest products.

“We dont think youre worth that much,” they replied.

Kitchen quit in early 1982. He didnt leave Wickstead Design Associates alone. His brother, Dan, went with him. They threw in with a couple of other engineers and set up shop in Garrys basement. Within a few hours of their first meeting, it resembled a mad scientists lab.

The owner of the house Kitchen was renting had left the basement unfinished. Exposed pipes and wiring hung from the open ceiling. Several workbenches had been shoved against the walls, and the four engineers spread out, cluttering every surface with computers and other equipment. Everyone did their own thing. Some guys experimented with the Apple II. Others tinkered with Ataris 2600. As yet, no one had a contract to develop anything. They were just tooling around until something came up. Coleco was the first to offer up something.

Founded in 1932 as the Connecticut Leather Company, Coleco pivoted to toys in the 1980s with Cabbage Patch Kids dolls. Now the owners were eyeing video games. Kitchen was confused when he received a call from a contract company offering him a deal with Coleco. “We have an in there,” the recruiter said, and explained that word had gotten around about Kitchens aptitude for programming 2600 software. “Theyre looking for somebody to do a port of Donkey Kong on the Atari. Are you interested?”

Kitchen brightened. “Sure.”

The terms of Kitchens partnership with the contract company dictated that they would split their share of the profits down the middle. Coleco wanted to ship Donkey Kong for the Atari in September. That meant production had to be finished by May to leave time for production and shipping.

Landing the deal made Kitchens day twice over. It meant steady work and steady pay, and it meant an opportunity to work on something red-hot. “It was the best one out at that point, head-and-shoulders above anything else in the marketplace,” he said of Donkey Kong. “It had a backstory, it had beautiful animation, and it wasn't blobs of unrecognizable graphics on the screen, unlike a bunch of other arcade games. There was a guy who ran around and jumped, and it looked very nice. I was aware it was a very high-profile adaptation.”

The guy who ran around and jumped was aptly named Jumpman, and a few years later would be rebranded as Mario. In Donkey Kong, Mario/Jumpman was a carpenter—later plumber-turned-rescuer-of-princesses—whose girlfriend Pauline had been abducted by the titular ape and hauled up to the top of one of Marios construction sites. The players goal was to guide Mario across four levels, or boards, each a single screen consisting of platforms and obstacles like rolling barrels, fireballs, gaps in floors, ladders, and lifts. Falling too far would kill Mario in cartoonish fashion, so precise jumps and careful timing were key.

Donkey Kong had been released in 1981 by a Japanese coin-op manufacturer called Nintendo. The game had single-handedly made the career both of its creator, a young industrial designer named Shigeru Miyamoto, and Nintendo, which had been struggling to get a foot in the door of the coin-op business with colorful but derivative rip-offs of shooters like Space Invaders and Galaxian. Kitchen had gravitated to the games colorful graphics and unique gameplay, setting it apart from the droves of shooters popular in arcades in the early eighties, as well as storytelling segments such as the cutscene that showed Donkey Kong climbing to the top of the construction site, Pauline clutched under one arm, and stomping the platforms to shatter and tilt them. Nintendo of America, the marketing arm of Osaka, Japan-based Nintendo Company Limited, sold through its initial run of Donkey Kong machines shortly after the games premiere in July. By October, NOA was shipping out 4,000 cabinets a week and still barely keeping up with demand.

Kitchen received a Donkey Kong coin-op to reference the games graphics and gameplay as he worked. “Since I was primarily concerned with the iconic first level with the slanted ramps and rolling barrels, that's the one I focused on first. It's also the level that was hardest to do, and took up the majority of my time.”

He scrutinized every pixel of DK, studying how characters and objects such as barrels and fireballs moved to recreate them on the 2600. He even took photographs of the screen and placed them by the Apple II keyboard. As hed done for Space Jockey, Kitchen wrote code for Donkey Kong on his Apple. Hed left his custom-made board and ribbon cable at Wickstead Design Associates, but he whipped up another in a month, one-sixth of the time hed needed to build the first one.

Kitchen had more wiggle room on Donkey Kong than hed had on Space Jockey, but only just. Instead of having to constrain his design to fit a two-kilobyte cartridge, he had double that amount. The rest of his toolset was just as spacious: Merlin, an assembler on Apple II that turned out a program in a few seconds, and a homemade chunk of 6502 assembly for the Apple II that took the binary file Merlin spit out and copied it into the memory on his 2600-compatible board. “I would assemble, wait thirty seconds, flip on the Atari, and there was the code, running on the Atari,” he said.

He delved into particulars. The 2600s screen, which the systems engineers had designated the playfield, functioned like a container. It could display scenery against a colored background, and hold five moveable objects named by Ataris engineers: two players, two missiles, and a ball. Player objects served as avatars of sorts. They could be tanks as in Ataris Combat, paddles like in Pong, spaceships as seen in Space Invaders—anything an artist could draw and a programmer could fit in memory. The missile, player, and ball objects could be moved around the screen as the programmer manipulated data held in the systems memory registers.

Each of the five moveable objects had predefined capabilities. For example, it only took a single instruction in code to move a player object, but the playfield had to be completely redrawn to reflect movement. Redrawing an object meant clearing every scan line, defined as one row of pixels. This, Kitchen knew, was where drawing Donkey Kongs first level got tricky.

About today's excerpt

This feature is excerpted, in slightly modified form, from the new book Arcade Perfect: How Pac-Man, Mortal Kombat, and Other Coin-Op Classics Invaded the Living Room by David L. Craddock. It's currently available in paperback and Kindle formats.

Working with the Atari 2600 was difficult because of the timing and handling engineers had to exert over its resources, as well as those of the television to which it output graphics and sound. Upon booting a game, programming routines synchronized the 2600 with the television set. The processor allocated memory for the five moveable objects, and each object consumed one bit of memory. The playfield took up forty bits, twenty for each half of the screen. Each slate of twenty bits could be told to duplicate or mirror the opposite side, and every individual pixel on the screen stored color information so the screen knew what color to put there. (The two missile objects assumed the color of their respective player objects.)

A raster televisions electron beam could be thought of as a paintbrush, and the pixels in each memory register as colors of paint on the artists palette. The brush started in the upper-left corner of the screen and, dabbing its bristles into the paint colors stored at each pixels position in memory, colored them in from left to right. When it finished with the first row, the brush moved down to the leftmost position of the next line and painted pixels again one by one, zooming across to the right.

Over and over, down and down it went until it reached the bRead More – Source