Atari Pong's source code doesn't exist
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Wait, no code at all‽
The original Pong cabinet from 1972 looks like a tiny yellow TV but under the hood it is closer to a digital clock than a computer. There is no CPU, no ROM, and absolutely no code. Instead every pixel, every bounce, and every blip comes from a nest of TTL (transistor-transistor logic) chips that shuffle voltages around in perfect rhythm with the display.
If you have ever joked about “hardware accelerated games,” this is the literal version.
If you open the machine you will not find a motherboard, you will find simple logic chips, a few dozen resistors and capacitors, and a crystal that keeps time. Together they produce the entire game state:
- Horizontal and vertical sync are generated by counters that tick in lock-step with a 14 MHz clock, these counters reset the beam just like a TV broadcast.
- The paddles are voltage ramps compared against a slider connected to the player knob, when the voltages match the circuit spits out a white rectangle for that scanline.
- The ball is a four-bit shift register that moves a single “1” bit left or right each pixel clock, flip-flops decide when to change direction after a collision, no fancy physics, just bits bouncing.
- Scoring uses decade counters that trigger the game-over LED once a player reaches eleven, when that happens the video generator stalls until you drop another quarter.
For anyone curious, here are the full schematic thanks to Atari’s old service documents:
Why build it this way?
In 1972 microprocessors were still lab toys, the Intel 4004 had only been around for a year and cost more than the rest of the cabinet combined. Discrete TTL was cheap, reliable, and easy to source, so Al Alcorn (the Pong designer) treated the circuit board like LEGO, wiring up gates until something on the oscilloscope looked like a bouncing square.
What this means for preservation
Because there is no binary to dump, preserving Pong is a matter of photographing the board and recording part numbers, then recreating the netlist in FPGA or software. Emulators such as MAME and DICE actually simulate each gate, which feels like using a sledgehammer to crack a walnut yet captures the original imperfections like jitter and analog fade.
TLDR
Pong has zero source code. The paddles, ball, and score are produced entirely by 1970’s logic chips wired into a self-contained video generator. The board is the software, so archiving the game means archiving the schematic rather than dumping a ROM.