List of Home Computers - Attributes

Attributes

Attributes are as typically advertised by the original manufacturer. Popular machines inspired third-party sources for adapters, add-on processors, mass storage, and other peripherals.

"Processor" indicates the microprocessor chip that ran the system. A few home computers had multiple processors, generally used for input/output devices. Processor speeds were not a competitive point among home computer manufacturers, and typically the processor ran either at its maximum rated speed ( between 1 and 4 MHZ for most processor types here), or at some fraction of the television color subcarrier signal, for economy of design. Since a crystal oscillator was necessary for stable color, it was often also used as the microprocessor clock source. Many processors were second-sourced, with different manufacturers making the same device under different part numbers. Variations of a basic part number might have been used to indicate minor variations in speed or transistor type, or might indicate fairly significant alterations to the prototype's capabilities. In the Soviet Bloc countries, manufacturers made functional duplicates of Western microprocessors under different part number series.

TV indicates the factory configuration produces composite video compatible with a home receiver. Some computers came with a built-in RF modulator to allow connection to the TV receiver antenna terminals; others output composite video for use with a free-standing monitor or external RF modulator. Still others had built-in or proprietary monitors. Often a composite video monitor (monochrome or color) would be substituted for the family TV. Some standard types of video controller ICs were popular, but see the very detailed List of home computers by video hardware for a discussion of video capabilities of different models. Memory and TV bandwidth restrictions meant that typical home computers had only a few color choices and perhaps 20 lines of 40 characters of text as an upper limit to their video capabilities.

Base mass storage was whatever came in the basic configuration. Some machines had built-in cassette drives or optional external drives, others relied on the consumer to provide a cassette recorder. Cassette recorders had the primary virtue of being widely available as a consumer product at the time. Typically a home computer would generate audio tones to encode data, that could be stored on audio tape through a direct connection to the recorder. Re-loading the data required re-winding the tape. The home computer would contain some circuits such as a phase-locked loop to convert audio tones back into digital data. Since consumer cassette recorders were not made for remote control, the user would have to manually operate the recorder in response to prompts from the computer. Random access to data on a cassette was impossible, since the entire tape would have to be searched to retrieve any particular item. A few manufacturers integrated a cassette tape drive or cassette-like tape mechanism into the console, but these variants were made obsolete by the reduction in cost of floppy diskette drives.

Floppy disk drives were initially very costly compared to the system purchase price. Plug-in ROM cartridges containing game or application software were popular in earlier home computers since they were easier to use, faster, and more reliable than cassette tapes. Once diskette drives became available at low cost, cartridges declined in popularity since they were more expensive to manufacture than reproducing a diskette, and had comparatively small capacity compared to diskettes. A few cartridges contained battery-backed memory that allowed users to save data (for example, game high scores) between uses of the cartridge.

Typically there were several models or variants within a product line, especially to account for different international video standards and power supplies; see the linked articles for variants and consequences of variations. "Compatibility" indicates some measure of compatibility with a parent type, however, sometimes incompatibility existed even within a product family. A "clone" system has identical hardware and is functionally interchangeable with its prototype; a few clone systems relied on illicit copies of system ROMs to make them functional.