User:Crotalus horridus/Sandbox/Commodore SX-64

The Commodore SX-64, also known as the Executive 64, was a compact briefcase-size version of the popular Commodore 64 home computer. It holds the distinction of being the first full-color portable computer.

The SX-64 featured a built-in five-inch composite monitor and a built-in 1541 floppy drive. It weighed 23lb (10.5kg). The machine was carried by its sturdy handle, which doubled as an adjustable stand. It was announced in January 1983 and released a year later, at $995.

Description
Aside from its built-in features and different form factor, there were several other subtle differences between the SX-64 and the regular C64. The default screen color was changed to blue text on a white background for improved readability on the smaller screen. This sometimes caused compatibility problems with programs that assumed the C64's default blue background. The default device for load and save operations was changed to the floppy drive. In addition, the cassette port and RF port were omitted from the SX-64 because it had a built-in disk drive and monitor, and thus no need for a tape drive or television connector. However, the omission made it impossible to use a standard C64 Centronics parallel printer interface without modification, since these interfaces used a connector on the cassette port to get +5V for operation. There were also subtle differences in the cartridge port, both electrically and in regards to its physical placement on the board, which made compatibility with certain C64 cartridges spotty.

An enhanced version of the SX-64 with dual floppy drives, known as the DX-64, was announced and a few have been reported to exist, but it is very rare. Some hobbyists installed a second floppy drive themselves in the SX-64's empty drive slot. A version with a monochrome screen called the SX-100 was announced, but never released.

Like the C64, the original SX-64's power supply limits the machine's expandability. Later units used a larger power supply that was originally intended for the DX-64.

Compatibility with Commodore RAM Expansion Units varies. Early SX-64 power supplies cannot handle the extra power consumption from the REU. The physical placement of the cartridge port can also prevent the REU from seating properly. In most cases, the 1700 and 1750 (128K and 512K) units intended for the C128 work more reliably with the SX-64 than the 1764 (256K) unit that was intended for the regular C64. Some SX-64 owners modified the devices to use an external power supply in order to get around the power supply issues.

History
The SX-64 did not sell well, and its failure has been variously attributed to its small screen, high weight, bad marketing, and smaller business software library than that of its competitors, the Osborne 1 (Zilog Z80 CPU, CP/M OS) and Compaq Portable (16-bit CPU, MS-DOS). In addition, the Osborne and Compaq computers were faster, and in the case of the Osborne, was competitively priced.

SX-64 sales have been estimated as low as 9,000 units from 1984 to 1986, when it was discontinued. In light of the relative frequency with which SX-64s are announced for sale on online auction sites this figure is with all probability much too low an estimate. The serial number database at SX64 Dot Net has records of 67 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.

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. The SX-64 did however gain a following with user groups and software developers, who could quickly pack and unpack the machine to use for copying software or giving demonstrations.

Technical information
Like the Commodore 64, except the following:
 * Built-in storage: 170K 5&frac14;" floppy disk drive (internal version of the Commodore 1541)
 * Built-in display: 5" (127mm) composite color monitor
 * Keyboard: separate unit, connected by cord to CPU unit
 * Cartridge port: placed on top of CPU unit, w/spring-loaded fold-in lid, cartridges inserted vertically (vs horizontally into back of C64)
 * I/O connectors:
 * no Datassette interface
 * no RF modulator & connector
 * 25-pin D-subminiature keyboard connector below right side of front panel
 * standard three-prong AC power connector (vs DIN plug from C64 "power brick" PSU)
 * Power supply: internal unit with transformer and rectifiers (vs external C64 PSU)
 * Extra features: floppy disk storage compartment above disk drive