Mimic Systems' Spartan

[email=mailto:brentm@telus.net]Brent Marykuca[/email], Mimic Systems' lead software developer, tells the story of the Spartan...

"Back in 1983 or '84 -- just after the release of the Commodore 64 -- a friend of mine in Victoria, British Columbia, had taken the original Apple II version of Space Invaders and made a few changes here and there to allow it to run reasonably well on the similarly-endowed C64. Of course, the prospect of writing a software product that would allow customers to run Apple II software on the newly-released, relatively inexpensive Commodore system was very appealling to some other people I knew, and they got all excited about the idea. Once it was shown that you really couldn't expect to do it in software, Mimic Systems was founded to develop a hardware solution. Fast forward to 1985, when I (at the tender age of 19) was hired to work as the lead software developer on a product dubbed "The Spartan" a Frankenstinian creation the likes of which we will not see again.

"The Spartan was an Apple II clone with a difference -- the difference being that it didn't come with a keyboard. Across the front of the machine were a series of edge connectors and cables that exactly matched up with the cartridge port, printer port, power input, etc. on the back of the C64. The idea was that you'd "mate" your C64 to the Spartan (all those connectors also showed up on the back of the Spartan), thereby creating a dual-processor system that would run Apple II and C64 software -- one of each simultaneously. A custom chip handled switching the keyboard and video between C64 and Apple II mode. In addition, the Spartan provided the user with four cartridge slots where there was only one on the C64, and a C64 to Apple Joystick converter.

"A particularly horrifying addition was the 'DOS Card', an Apple II disk controller that you installed *inside* the Commodore 1541 disk drive, between the drive mechanism and the 1541 logic board. In 1541 mode, the 'DOS Card' simply passed signals through from the 1541 logic, but at the flick of a switch (F6, I believe) it would take over the mechanism and turn the thing into an Apple II drive. As you can imagine, the potential for grave damage to both Apple II and 1541 diskettes was enormous and often realized.

"The Spartan hardware was highly 'customizable' for its day. It contained no less than 24 jumper blocks on the main board and CPU card so that the user could customize interrupts, ROM mapping, power-up state (C64/Spartan), reset capabilities (can the Spartan reset C64 and vice-versa), address mapping of certain hardware features, joystick conversion features and availability of additional RAM banks.

"The software features of the Spartan included a compatible Applesoft BASIC -- very compatible, since it was created by disassembling the binary from the the Applesoft ROM and reordering assembly level instructions so that the binary image of the software would be different, but behavior when run would be identical. The Spartan had software control of audio and video switching between the two systems' video modes, as well as a mixed audio mode. An Apple-like assembly language monitor was available on the Commodore side.

"The software contained a 'slave mode' where by using custom commands in the monitor (also available via BASIC on both machines), you could transfer data between the two systems and even execute programs on the slave system. The most interesting example of the use of this feature was a 3-D graphics demo in which some of the calculation tasks were offloaded to the slave machine.

"The Spartan actually shipped to customers some time in late 85-early 86, if I recall correctly. Apart from the technical challenges, the whole Mimic Systems story was pretty sordid, characterized by weekly changes to the design by the president of the company (he would typically change it back the following week), frequent unmotivated firings of technical staff (he fired three in one day I remember, one guy because he was watching the plotter draw a circuit board design rather than working), and a draconian management style (we were paid by the hour and required to 'clock out' to go to the bathroom). The saga ended for me in early 1986 when I quit shortly after the president of the company wrote himself a big cheque from the payroll account and took off for South America -- according to legend, anyhow.

"Mimic Systems' Spartan: The Low Point in Apple II cloning!"

The back of the Spartan. Note that the Commodore's ports pass through so that the Spartan can be connected at all times.

The Spartan's motherboard.

Each of the connectors and DIN plugs on front connected to a corresponding port or connector on the back of the C64. On the right side of the box is the external C64 cartridge slot (there were three more inside), and the three reset buttons (C64, C64 with selected cartridge, and Spartan). The reset buttons are described in the manual as "The first, and probably most functional part of the Spartan system."

The inside of the lid with some of the signatures visible. They're hard to read, but one or two of them is nearly visible. Brent's is the one right above "Larry Wilson".

The Spartan's first advertisement, appearing in "Ahoy!" magazine.

Aaron supplied this second advertisement, found on page 9 of the January 1986 issue of Compute!'s Gazette (Issue 31, Vol. 4, No. 1).