The 8251 is a Programmable Communication Interface controller and is found inside a DAP4 CPU board 1528-xx and form the interface between the CPU board electronics and the external personality interface board.
TC550 Memory Datasheet
The TC550 is a 256 word by 4 bit memory and two of these memories are usually found inside a DAP4 CPU board 1528-xx. They are extremely low power CMOS memories and as such are used as NVR (None-Volatile RAM) by the CPU board to store user changeable configuration data.
The AY-3-1015 is a Universal Asynchronous Receiver/Transceiver IC (UART) and controls the data communication between the ALME channel and the connected device. 1882-00 and 1882-01 ALME
The MC14411 is a bit rate generator IC and is used as the master clock rate generator within the 1882-00 and 1882-01 ALME