It was announced in January 1983 and released eleven months later in December 1983, at $995 USD (equivalent to $2,918 in 2023).

[5] Differences, electrically and in placement on the board, means that there are compatibility problems with some C64 cartridges.

When it is powered up, the screen sends out the C64 breadbin "blue" background with the typical 38911 BASIC BYTES FREE, and immediately under the READY prompt a statement of RAM is displayed.

A version of the SX-64 with dual floppy drives, known as the DX-64, was announced, but the press reported by early 1985 that plans for its release had been suspended.

The SX-64 did not sell well, and its failure has been variously attributed to its small screen, excessive weight (10.5 kg or 23.1 lb), poor marketing, and smaller business software library than that of its competitors, which included the Osborne 1 and Kaypro II (Zilog Z80 CPU, CP/M OS) and Compaq Portable (16-bit CPU, MS-DOS).

The serial numbers of over 130 SX-64s from series GA1, GA2, GA4, GA5 and GA6, with serial numbers ranging over 49,000 for series GA1, 1,000 for GA2, 17,000 for GA4, 11,000 for GA5, and 7,000 for GA6 have been reported[6] Some would-be buyers waited instead for the announced DX-64, which never became widely available due to the slow sales of the SX-64, creating a Catch 22 situation similar to that endured by Osborne after announcing an improved version of its computer.

favorably reviewed the SX-64, stating that the keyboard was better than the 64's, the monitor "isn't hard to read at all", and the disk drive was durable enough for travel.

While criticizing the lack of any provision for internal or external battery power, the magazine concluded that the average $750–800 retail price was "worth every penny!".