IBM PALM processor
The PALM is a 16-bit central processing unit developed by IBM. It was used in the IBM 5100 Portable Computer, a predecessor of the IBM PC, and the IBM 5110 and IBM 5120 follow-on machines. It is likely PALM was also used in other IBM products as an embedded controller.
IBM referred to PALM as a microprocessor, though they used that term to mean a processor that executes microcode to implement a higher-level instruction set, rather than its conventional definition of a CPU on an integrated circuit. The PALM processor was a circuit board containing 13 bipolar gate arrays packaged in square metal cans, 3 conventional transistor–transistor logic ICs in dual in-line packages, and 1 round metal can part.
PALM has a 16-bit data bus, with two additional bits used for parity. PALM can directly address 64KB of memory. The IBM 5100 could be configured with up to 64+KB of Executable ROS and up to 64KB of RAM. A simple bank switching scheme was used to extend the address space.
In 1973, the IBM Los Gatos Scientific Center developed a portable computer prototype called SCAMP based on the PALM processor with a Philips compact cassette drive, small CRT display, and full-function keyboard.
