The Executive 64s: SX-64, DX-64, Executive 64, SX-100, SX-500

SX-100

Faceplate of the SX-100 (24K, courtesy Bo Zimmerman)

Introduced January 1983, with the DX-64.
Hardware Identical to the 64. Upgraded Kernal; missing the cassette port and the RF modulator outputs. Cartridges are accepted through the top, not the back. Integrated 1541 disk drive, supposedly choice of one or two, and a 5-inch black and white composite monitor.
Graphics and Sound Identical to the 64.
Eventual Fate As such, never released -- but see the DX entry.

SX-64, DX-64

Complete Views of the SX-64 (.jpg, my unit)
Portrait (with "saddlebag", 84K) | Ports (47K) | Backplate (43K) | Case Off (125K) | Screenshot (26K)

Additional Views of the SX-64 (.jpg, except where noted): Portrait (19K, courtesy Markus Mehring) | SX-64 Front Panel (10K, courtesy Marko Mäkelä, Andreas Boose and George Page; cropped/shrunk) | SX-64 Front Panel (.gif, 12K, identical to previous)

aka The name game is interesting. The computer was introduced as the SX-64 and released as the Executive 64, but everyone calls it the SX anyway. And the case has both names on the front! In Sweden, according to Peter Karlsson, the SX-64 (as sold by Handic Computers) was called the VIP-64.
Introduced The DX-64 was announced January 1983 with the SX-100; the SX-64 appeared later that year (see Eventual Fate).
Hardware Identical to the 64. Upgraded Kernal (new startup colours, cyan on white with cyan border and "COMMODORE SX-64" startup banner; Kernal defaults to device 8 instead of device 1); missing the cassette port and the RF modulator outputs. Cartridges are accepted through the top, not the back. Integrated 1541 disk drive and 5-inch colour composite monitor. The DX-64, the original two-drive version, has two drives (drive 1 on top and drive 0 below, in the same position as the single drive appears on the SX).
Graphics and Sound Identical to the 64.
Eventual Fate The DX-64 was first announced, though not by name, in January 1983 with the SX-100; however, it was released in the single-drive form now commonly called the SX-64 as the Executive 64 in May 1983 for MSRP US$1000. After initial optimism, it was not a strong seller due to its weight, price and unfortunate similarities to the Osborne-1, another computer ahead of its time. Nevertheless, the original DX-64 did apparently escape; several working units have been confirmed to exist by Marc Walters. There is at least one known of in the U.S., and a few in Germany.

Comments
The SX-100 and the DX-64 were supposed to coexist side by side, and the SX-64 was never even part of Commodore's original rollout. At the Consumer Electronics Show that year (as reported in the March 1983 COMPUTE!), Commodore announced that the SX-100 would sell for $995, and "a colour TV version with two disk drives for $1295" (presumably the DX-64). Naturally, this didn't play out in practice, because the most obvious remnant of the ill-fated Executive series is the SX-64, which has only one disk drive and the colour screen. It is interesting that the Creative Computing photograph above shows a "color" SX-100, running the SX-100 demonstration program, but is obviously a DX-64.

According to Travis Little, the SX/DX series' top-loading cartridge port in early models had improper shielding, being literally just a ribbon cable to the mainboard, and REUs and later cartridges would not work correctly in it. The problem was so bad that Commodore was forced to put out a service pack to replace the ribbon cable with a more sturdy one.

Commodore may have had several expansion options in mind specifically for the SX/DX series, none of which ever came to fruition (or possibly even past rumour); as one that got at least to rumour stage, there is a mention in RUN 5/84 about a possible TV tuner package for the SX, but Commodore never confirmed or demonstrated the product.

The SX-64 carries one important distinction: it was the first colour portable computer released. Even though it didn't sell well, it has aged particularly gracefully, and intact units command a respectable price today due to its novelty value. Certainly, an SX-64 beats throwing a 1702, a 1541, a 64 and a power supply in the car, and my personal stable of SX-64s (I own three) see ample use at road shows and conventions. For a relatively uncommon unit during its heyday, they are now becoming more and more routinely seen and used by the modern Commodore retro-enthusiast.

It is worth noting in this entry that the SX-64 was not the only portable Commodore system; one particularly interesting European variant is the unrelated PDC Clipper. Not a Commodore unit, the PDC Clipper was a "briefcase" system based around a 64 motherboard with 3" (not 3.5") floppy, modified keyboard, custom menu in ROM and an electroluminescent high-resolution flat screen. Manufactured by a Siemens branch in Belgium, the company flamed out extremely quickly after the units were released. In Germany, the SX-64 was available in an aftermarket-modified form as the Tesa 6240 (picture, 38K, courtesy Nicolas Welte), a specialized unit used as a control computer for label printing systems with custom ROMs, a green monochrome monitor and no SID. Keyboard stickers were also present for the unit's custom functions. Like the PDC Clipper, the Tesa 6240 was not associated with Commodore officially either.

SX-500

Introduced Never officially.
Hardware, Graphics and Sound Identical to the original Amiga 500.
Eventual Fate Scrapped prototype. Only three were made.

Comments
Yes, Virginia, this really is an Amiga 500 crammed into an SX-series case. I had the pleasure of checking out this unit at the Vintage Computer Festival 5.0. Thanks to Dale Luck for the scoop.

The SX-500 is not a mockup, but totally functional, and fairly advanced for a small-production-run prototype. Nevertheless, its SX-64 roots die hard; while it has an Amiga-specific keyset, the cursor keys are (strangely) over where the function keys normally lie on the SX-64; and the top cartridge slot is clearly evident even though it had been filled in and closed off. In addition to the gimme-disk animation, the SX-500 seemed also excellent at displaying Guru Meditation errors. Well, heck, it *has* to be an Amiga if it does that. :-)

The SX-500 was created by Commodore engineer Hedley Davis in 1987, who later worked on the "Hedley" A2024 monitor and the A3000. It isn't known if Commodore had specific production plans in mind or whether the SX-500 was simply a trial balloon for a later full-fledged Amiga portable.