Back in the nineties I designed a product with a Z182, which is a Z180 with some nice extra goodies, the important one the (IIRC) ASSC; which was the only synchronous serial controller capable of properly talking HDLC to some weird industrial machine (which probably used the Zilog ASCC too).
The Z182 also had a 'MIMIC" which allowed direct connection to a PC ISA bus where it looked like a 16550 compatible UART. Made for a simple interface.
Basically an EPROM, SRAM, GAL, Z182 and a couple of RS485 transceivers. In a later revision the EPROM, SRAM and GAL were replaced by a PSD854.