# Atari 2600: Pitfall\!

A 1980 Atari 2600 with its joystick and the Pitfall\! cartridge: see how the console races the TV beam, then play the jungle on the period TV

By Numa

Topic: Games

[Open the interactive Jig](https://ask.jig.com/j/yKAjfRFdySr4)

## Guide

### 1. The Atari 2600

This is the 1980 four\-switch Atari Video Computer System \(model CX2600\-A\), with its CX40 joystick and the Pitfall\! cartridge from Activision \(1982\)\. The console is playing the game by itself on a period colour portable TV\.

Drag empty space to turn the room\. Grab the joystick at any time to take over\.

### 2. Switches and the cartridge slot

The woodgrain front and ribbed top carry four chrome switches: POWER and TV TYPE \(colour or black\-and\-white\) on the left, GAME SELECT and GAME RESET on the right\. The difficulty switches sit on the back\. The game lives on the cartridge: plug it in and the console runs it straight from its ROM\.

Click a switch to flip it\. Click the cartridge to pull it out\.

### 3. The CX40 joystick

One stick and one red button\. Inside, the stick presses on four switches \(up, down, left and right\) and the button closes a fifth\. The console simply reads which of these five contacts are closed\. Watch the stick and button follow the moves of the game playing itself\.

Drag the stick to move Pitfall Harry\. Click the red button to jump\.

### 4. Three chips do everything

The 6507 processor runs the cartridge program at about 1\.19 MHz\. The 6532 RIOT holds all of the RAM \(128 bytes\), reads the joystick and switches and keeps a timer\. The TIA \(Television Interface Adaptor\) makes the picture and the sound\.

### 5. Racing the beam

The 2600 has no frame buffer\. The TV beam sweeps 262 lines every frame, and the TIA only knows what to draw on the current line\. While the beam crosses each line, the program has 76 processor cycles to set the colours, the 40\-cell background pattern and the sprite positions for the next one\. Here a frame takes seconds instead of a sixtieth\.

Lines the beam has passed glow brightly; the rest are fading from its last pass\.

### 6. 128 bytes of memory

Everything the game remembers fits in 128 bytes: the screen you are on, Harry's position and jump, the vine's swing, the score, the timer, lives, the logs and which treasures are taken\. Each dot is one bit\. Watch them change as the game plays\.

### 7. 255 screens from one byte

The jungle is not stored as a map\. One byte describes the current screen: the scene, the trees and the hazard\. Stepping right shifts the byte and feeds back four of its bits \(a linear feedback shift register\), giving all 255 screens and 32 treasures before it repeats\. Stepping left runs it backwards\. The counter at the top shows how many screens have passed\.

### 8. Your turn

Drag the joystick to run, and push it up to climb a ladder\. Click the red button to jump; jump into a vine to catch it and pull down to let go\. Collect the treasures within 20 minutes and avoid tar, water, crocodiles, the cobra, fire, scorpions and logs\.

Release the stick and click the button just after running for a running jump\.