The PC-BIT was an ISDN ISA card for desktop PCs that ingeniously did away with a bunch of proprietary components and implemented a fair chunk of the required protocols in software (initially in its own on-board low-end x86 CPU, and later on mostly off-loaded to the host PC).

Board development was sponsored by Portugal Telecom (which sold the board as its Cyberkit RDIS product) and was later moved to a hardware-centric INESC spin-off called Octal (which seems to have vanished).

This is what the early PC-BIT cards looked like

At INESC, I worked on the multi-link PPP support for Windows (9x and NT up to 4.0), which was a lot of fun (even if routinely frustrating).


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