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A B series Flip-Chip
Flip-Chip was a DEC registered trademark, named after the "flipchip" component mounting technique which quite rapidly faded from fame. The name was retained although the majority of Flip-Chips never really were flipchip-mounted as it became apparent that the flipchip mounting technique was highly unreliable. Flip-chips were used in the DEC PDP-7 (Referred to in documentation as the "FLIP CHIP"), PDP-8, PDP-9 and PDP-10, beginning on August 24, 1964.
In practice, they performed generic, simple functions, similar to an integrated circuit. They were approximately 4 inches long and 2.5 inches wide. Each had 36 connectors, 18 on each side.
There appeared to be some confusion inside DEC at the time, as various manuals refer to it as "FLIP CHIP", "Flip Chip", "FLIP-CHIP", "Flip-Chip" and "Flip Chip", with trademark and registered trademark symbols.
Flip-chips in different forms and a rainbow of colours, in a PDP-8.
The various families were colour-coded, and the first letter denoted a colour, which was also visible on the handle.
The M stands for magenta. Part of this line is simple TTL-level logic, while later on, it became quite complex, see list of DEC part numbers. They replaced the R series which used discrete transistors with integrated circuits.
Power supply: 5 V
Operate at up to 6 MHz
The R stands for Red. Slower logic than the B series, but cheaper. Used extensively in the I/O circuitry of computers.