SPECTRAVIDEO SV-603

The Spectravideo SV-603 (also written as SVI-603) is a ColecoVision Game Adapter that converts the Spectravideo SVI-318 and SVI-328 home computers into fully functional ColecoVision game consoles. Announced in 1983 at a retail price of $70, it allowed Spectravideo owners to access the entire library of ColecoVision game cartridges.

This was possible because the Spectravideo computers share core hardware components with the ColecoVision — both use the Zilog Z80 CPU, Texas Instruments TMS9918-family Video Display Processor, and compatible sound hardware. The SV-603 adapter provides the missing piece: an 8 KB ROM containing the ColecoVision BIOS and a ColecoVision cartridge slot, bridging the gap between the two platforms.

The adapter connects to the host computer via the 50-pin expansion slot on the rear of the SVI-318 or SVI-328. When connected, the Spectravideo computer effectively becomes a ColecoVision console, with the ColecoVision BIOS taking over the system. The adapter also includes two ColecoVision-compatible controller ports, since the SVI’s own keyboard and joystick ports are disabled while the adapter is active.

The Spectravideo SV-603 represents a unique approach to ColecoVision compatibility — rather than being a standalone clone console, it is an expansion peripheral that leverages existing compatible hardware already present in the host computer.

Spectravideo International Ltd. was a consumer electronics company that produced the SVI-318 and SVI-328 home computers in 1983. The company’s computers were significant in computing history because the SVI-328’s hardware design directly influenced the creation of the MSX computer standard.

Spectravideo Canada was headquartered in Toronto, and the company maintained offices internationally. The SVI-318 and SVI-328 were sold primarily in North America, Europe, and Australia. Both machines featured Microsoft Extended BASIC and were designed as affordable home computers with gaming capabilities.

The SV-603 ColecoVision adapter was one of several expansion peripherals Spectravideo offered. Others included the SVI-601/601A Super Expander (multi-slot expansion chassis), SVI-801 Disk Controller, SVI-802 Centronics printer interface, and the SVI-903 data cassette drive. The company later released MSX-compliant successors including the SVI-728.

The SV-603 was a clever product that leveraged the shared Z80/TMS9918 architecture between Spectravideo and ColecoVision hardware to give SVI owners access to a large existing game library — the same hardware affinity that Bit Corporation would later exploit with the DINA 2-in-1 and Bit 90.