Sinclair ZX Spectrum Computer - Early Issue
The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research Ltd. Referred to during development as the ZX81 Colour and ZX82, the machine was launched as the ZX Spectrum by Sinclair to highlight the machine's colour display, compared with the black-and-white of its predecessor, the Sinclair ZX81.
The Spectrum was released in eight different models, ranging from the entry level model with 16K RAM released in 1982 to the ZX Spectrum +3 with 128K RAM and built-in floppy disk drive in 1987. All machines released after the Spectrum 128K in 1986 were designed and manufactured by Amstrad, after the purchase of the Sinclair name and IP earlier that year.
The Spectrum was among the first mainstream audience home computers in the UK, similar in significance to the Commodore 64 in the USA.
The introduction of the ZX Spectrum led to a boom in companies producing software and hardware for the machine.
The Spectrum is based on a Zilog Z80A CPU running at 3.5 MHz (or NEC D780C-1 clone). The original model Spectrum has 16K (16×1024 bytes) of ROM and either 16K or 48K of RAM. The 16K model cost £125, while the 48K model cost £175. Hardware design was by Richard Altwasser of Sinclair Research, and the machine's outward appearance was designed by Sinclair's industrial designer Rick Dickinson.
The Basic was written by Cambridgeshire company Nine Tiles who have donated a great many machines and associated paperwork to the museum, including this early iteration of the computer and the Spectrum Prototype, the very origins of the machine.
Early model one ZX Spectrums were manufactured with light-grey keys instead of the blue-grey used in later models. Somewhere around 14-16000 model ones were produced; this model has serial number 001-001537. This example has the original grey key mat, but due to a high failure rate, it is possible to find issue one boards with later blue keys, as Sinclair would repair and rehouse the boards.
This example in our collection was originally a 16K model, but has the daughterboard fitted making it a 48K version.
The machine has been reworked by Sinclair, including rewiring, and a poorly fitted chip, some issue one machines have very ugly repairs or modifications. Affectionately known as the dead cockroach fix, there is usually a tiny board fitted upside down to correct a timing error in the ULA, this machine has an upside down chip, more wires and electrical tape.
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This exhibit has a reference ID of CH54307. Please quote this reference ID in any communication with the Centre for Computing History.
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