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IBM PALM processor

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This is an old revision of this page, as edited by 99Electrons (talk | contribs) at 05:51, 9 December 2018 (Don't use the package type as an adjective (it's a little confusing); not sure if the article meant the DIPs were conventional or if the TTL ICs were (conventional probably meant standard 74x series),). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
IBM PALM processor
General information
Launched1975

The IBM PALM processor (Put All Logic in Microcode) is a board-level 16-bit central processing unit (CPU) used in the IBM 5100 Portable Computer, a predecessor of the IBM PC. PALM was also used in the IBM 5110 and IBM 5120 follow-on machines. PALM was likely 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 (TTL) 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 64 KB (64 KiB) of memory. The IBM 5100 could be configured with up to 64+ KB (APL + BASIC ROMs make 64+ KB) of Executable ROS (ROM) and up to 64 KB 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 (Special Computer APL Machine Portable) based on the IBM PALM processor with a Philips compact cassette drive, small CRT and full function keyboard.[1]

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