Type-in program
It was meant to be entered via the keyboard by the reader and then saved to cassette tape or floppy disk.
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.
Machine code programs were long lists of decimal or hexadecimal numbers, often in the form of DATA statements in BASIC.
A reader would take a printed copy of the program listing, such as from a magazine or book, sit down at a computer, and manually enter the lines of code.
In the latter case, the opcodes and operands of the machine code part were often simply given as DATA statements within the BASIC program, and were loaded using a POKE loop, since few users had access to an assembler.
In some cases where the version of ASCII used on the type of computer the program was published for included printable characters for each value from 0–255, the code could have been printed using strings that contained the glyphs that the values mapped to, or a mnemonic such as [SHIFT-R] instructing the user which keys to press.
By the mid-1980s, recognising this demand from readers, many US-published magazines offered all of each issue's type-ins on an optional disk, often with a bonus program or two.
Some UK magazines occasionally offered a free flexi disc that played on a turntable connected to the microcomputer's cassette input.
[2] These programs were often graphic demos or meant to illustrate a technical quirk of the computer's architecture; the text accompanying the graphics demo programs would avoid explicitly describing the resultant image, enticing the reader to type it in.
[4]Upon Ahl's departure from DEC in July 1974, he initiated a bimonthly magazine titled Creative Computing while serving as an educational marketing manager at AT&T.
The professional and business-oriented journals such as Byte and Popular Computing printed them less frequently, often as a test program to illustrate a technical topic covered in the magazine rather than an application for general use.
Antic stated in 1985 that its staff "spends a good portion of our time diligently combing the incoming submissions for practical application programs.
We receive a lot of disk directory programs, recipe file storers, mini word processors, and other rehashed versions of old ideas".
[8] While most type-ins were simple games or utilities and likely only to hold a user's interest for a short time, some were very ambitious, rivaling commercial software.
To prevent errors when typing in listings, most publications provided short programs to verify that code was entered correctly.
The MIKBUG machine code monitor for the Motorola 6800 of the late 1970s incorporated a checksum into its hexadecimal program listings.
Upon successful validation, the program was saved as a binary file and the BASIC code no longer needed.
