|Developer:||Innovation Computer Corporation|
The SSI 2001 is a sound card that was manufactured by Innovation Computer Corporation. It is essentially a Commodore SID chip for PCs, in particular, the 6581. The card retailed for around $130.00 and includes a mono RCA output jack and a game port. In addition, there are 3 banks of jumpers that allow you to enable or disable the joystick port, control the joystick sensitivity, and change the sound port address from its default 280hex to either 2A0hex, 2C0hex or 2E0hex.
While in use, the card consumes 32 consecutive I/O ports, the last 3 probably undefined, like on the C64. The 6581 is clocked using the 14.318180 MHz clock of the ISA bus. This clock signal is divided by the counter and flip flops on the board by 16 to produce a base frequency of 0.89488625 MHz. By contrast, the base frequency of the SID in an NTSC C64 is 1.02272714 MHz and a PAL C64 is 0.98524851 MHz. The POTX and POTY pins, which were used on the C64 to read mice and paddle movements, are not connected on the SSI 2001 board, since the PC has other ways to read them.
Despite the popularity of the SID in the Commodore 64 scene, particularly American companies were already abandoning the C64, and cards that offered FM synthesis (including the Ad Lib Music Synthesizer Card) were already on the market, so the SSI 2001 never caught on in the PC market and was only supported by a handful of games. The lack of support also caused a lack of production and only a couple of working cards are know to exist.
Emulation has been added to DOSBox unofficially, but to get support, you must rebuild DOSBox from source. The emulation is based on reSID.
- nerdlypleasures.blogspot.com/2014/01/sid-and-dos-unlikely-but-true-bedfellows.html - Nerdly Pleasures.
- archive.org/details/Computer_Gaming_World_Issue_63/page/n17 - Comparison in Computer Gaming World Number 63, September 1989.