The Sinclair ZX81
, launched in 1981, was the first cheap mass-market home computer. However, it lacked a hard drive, storing data instead on audio tape cassettes. However, Byte
magazine revealed that a third-party supplier, Hindsight Engineering, was introducing a 5-megabyte hard disk for the ZX81. (At the time, 5 megabytes was considered an extremely large size):
Responding to an obvious need of ZX81 owners for more data storage space, Hindsight Engineering has developed a 5-megabyte hard-disk system for the Sinclair ZX81. The system is available in either assembled or kit forms. The kit includes instructions for building your own clean room for kit assembly. A DOS will soon be available.
Hundreds of readers wrote to the magazine requesting more information.