SWTPC

Southwest Technical Products Corporation, or SWTPC, was an American producer of electronic kits, and later complete computer systems.

Most of these kits were intended for audio use, such as hi-fi, utility amplifiers, and test equipment such as a function generator based on the Intersil ICL8038.

For example, the new Signetics NE565 phase-locked loop chip was the core of a subsidiary communications authority (SCA) decoder board, which could be built and added to an FM radio to demodulate special programming (often, background music) not previously available to the general public.

FCC regulations did not ban reception or decoding of radio transmissions, but SCA demodulation had previously required complex and expensive circuitry.

Another popular new integrated circuit was the Signetics NE555, a versatile and low-cost timing oscillator chip, which was used in signal generators and simple timers.

SWTPC's SS-50 backplane bus was also supported or used by other manufacturers: (Midwest Scientific, Smoke Signal Broadcasting, Gimix, Helix, Tano, Percom Data, Safetran), etc.

Technical Systems Consultants, first of West Lafayette, Indiana (ex Purdue University) and later of Chapel Hill, North Carolina, was the foremost supplier of software for SWTPC compatible hardware.

Their software included operating systems (Flex, mini-FLEX, FLEX09, and UniFLEX) and various languages (several BASIC variants, FORTRAN, Pascal, C, assemblers, etc.)

He later expanded the language to 4K, adding support for floating-point arithmetic; this implementation was unique among BASIC interpreters by using Binary Coded Decimal to nine digits of precision, with a range up to 1099.