The port is a remnant of an abandoned design feature for addition of internal RAM and a clock for time keeping.
[3] The A1200 was the only Amiga model to have this unique 22-pin connector (some revisions of the A1200 motherboard have additional non-functional pins).
However, as the address and data signals used by the interface are available through the internal expansion connectors of other Amiga models, clock port adaptors were later created by third-party developers for these systems.
[4] Due to the popularity of clock port devices, developers even included one or more compatible clock port interfaces on Amiga Zorro boards to allow hosting such devices on these systems.
[5][6] Essentially, the connector provides an 8-bit data interface with limited addressing.