Commodore SX-64

Commodore SX-64

Release date	1984
Discontinued	1986
Operating system	Commodore KERNAL Commodore BASIC 2.0
CPU	MOS Technology 6510 @ 1.02 MHz (NTSC version) @ 0.985 MHz (PAL version)
Memory	64 kB RAM + 20 kB ROM
Graphics	VIC-II (320 x 200, 16 colors, sprites, raster interrupt)
Sound	SID 6581 (3x Osc, 4x Wave, Filter, ADSR, Ring)
Connectivity	2x CIA 6526 Joystick, Power, Cartridge (modified), A/V, IEEE-488 Floppy/Printer, GPIO/RS-232
Predecessor	Commodore VIC-20
Successor	Commodore 128

The Commodore SX-64, also known as the Executive 64, or VIP-64 in Europe, is a portable, briefcase/suitcase-size "luggable" version of the popular Commodore 64 home computer and holds the distinction of being the first full-color portable computer.^[1]

The SX-64 features a built-in five-inch composite monitor and a built-in 1541 floppy drive. It weighs 10.5 kg (23lb). The machine is carried by its sturdy handle, which doubles as an adjustable stand. It was announced in January 1983 and released a year later, at US$ 995.^[2][3]

Description

Aside from its built-in features and different form factor, there are several other differences between the SX-64 and the regular C64. The default screen color is changed to blue text on a white background for improved readability on the smaller screen. This can cause compatibility problems with programs that assume the C64's default blue background. The default device for load and save operations is changed to the floppy drive. The cassette port and RF port were omitted from the SX-64 because it has a built-in disk drive and monitor, and therefore no need for a tape drive or television connector. These changes make it impossible to use a standard unmodified C64 Centronics parallel printer interface, since it took a +5V voltage from the cassette port. Differences electrically and in placement on the board, means that there are compatiblity problems with some C64 cartridges.

The original SX-64's (built in) power supply limits the machine's expandability.

Later units (from GA4 and on) use a larger power supply 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 prevent the REU from seating properly. The 1700 and 1750, 128K and 512K units intended for the C128, are said to work more reliably with the SX-64 than the 1764 unit that was intended for the regular C64. Some SX-64 owners modify Commodore REUs to use an external power supply in order to get around the power supply issues.

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. Instead of an extra floppy drive, a modem could also be built in above the first drive. 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.

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.

The exact number of SX-64 sold from 1984 to 1986, when it was discontinued, is unknown. 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^[4]

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: 170 kB 5¼" floppy disk drive (internal version of the Commodore 1541)
• Built-in display: 5" inch (127 mm) composite color monitor (CRT)
• 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:
  • Serial interface (rear)
  • Video out connector (rear)
  • User Port (rear)
  • Cartridge Port (hidden under to flaps on the top)
  • No Datassette interface
  • No RF modulator & connector
  • Non-standard 25-pin keyboard connector below right side of front panel. The connectors are similar but not identical to D-subminiature connectors and notoriously hard to find today^{[citation needed]}
  • Standard three-prong AC power connector (vs C64 DIN plug to "power brick" PSU)
• Power supply: Internal unit with transformer and rectifiers (vs external C64 PSU)
• Extra features: Floppy disk storage compartment above disk drive which could be used to build in an extra floppy drive or compatible sized modem

References

1. ^ Commodore SX-64 Portable
2. ^ Commodore SX-64 portable computer
3. ^ Mace, Scott (February 6, 1984). "Commodore introduces new family of computers". InfoWorld (Menlo Park, CA: Popular Computing) 6 (6): pp 11–12. ISSN 0199-6649. http://books.google.com/books?id=gC4EAAAAMBAJ&pg=PA11.  "[Don Richards, Commodore USA president,] also said that the SX-64 computer, a $995 portable version of the Commodore 64 with built-in color monitor, has been a sellout everywhere."
4. ^ database at SX64.net

External links

• SX64 Dot Net
• SX-64 schematics (PDF format, zipped)
• Commodore SX-64 Paper Model
• C64 Preservation Project Preserving original C64 hardware and software