|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. The possible supported addresses include 280, 2A0, 2C0 or 2E0--280 is the default.
While in use, the card consumes 32 consecutive I/O ports (3 presumably mirrored or unused). 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 are not connected on the SSI 2001 board, so the card cannot support the functionality provided by these pins.
Despite the popularity of the SID in the Commodore 64 scene, the card never caught on in PC market and was only supported by a handful 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.