A type-in program or type-in listing was computer source code printed in a home computer magazine or book. It was meant to be entered via the keyboard by the reader and then saved to cassette tape or floppy disk. The result was a usable game, utility, or application program.
Type-in programs were common in the home computer era from the late 1970s through the early 1990s, when the RAM of 8-bit systems was measured in kilobytes and most computer owners did not have access to networks such as bulletin board systems.
Magazines such as Softalk, Compute!, ANALOG Computing, and Ahoy! dedicated much of each issue to type-in programs. The magazines could contain multiple games or other programs for a fraction of the cost of purchasing commercial software on removable media, but the user had to spend up to several hours typing each one in. Most listings were either in a system-specific BASIC dialect or machine code. Machine code programs were long lists of decimal or hexadecimal numbers, often in the form of DATA statements in BASIC. Most magazines had error checking software to make sure a program was typed correctly....