The PALM processor is an entire board. "Microcode" does not imply microprocessors, it was actually thought to be one of the major properties of 2nd generation machines, long before this.

A PALM processor can be seen here: https://hackaday.com/2023/12/19/bringing-apl-to-the-masses-t.../

[Edit] To be fair, the Wikipedia article on the PALM processor does mention this: "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."