Some years ago I recovered a couple of boards out of copiers in e-waste. One was still mounted in its aluminium chassis, with a power socket, power switch, RS-232 connector, and power transformer.
Z80 CPU running at 4.9562 MHz
Z8430 counter timer chip
Z8440 SIO chip
2764 8kB EPROM (removed from socket and contents dumped to a file)
8kB static RAM
LSTTL glue chips
RS-232 interface chips
A LM339 quad comparator, suggesting some kind of analog input
7805, 7808, and 7908 regulator chips for +5, +8, and -8V supplies
6 darlington power driver transistors, 3 each of TIP130 and TIP135
A huge transformer with one winding supplying +5V for the processor and chips and another winding for the positive and negative power lines to the power transistors
ROM space is from 0x0000 to 0x7fff. 27128 (16kB) EPROMs can be used without modification, 27256 (32kB) EPROMs can be used with one address line modification
RAM space is from 0x8000 to 0xffff. 32kB RAMs can be used by changing one bridge track to another on the board
74LS138 1 of 8 decoder occupies 0x00 to 0x07
Z8440 SIO occupies 0x08 to 0x0f
Z8430 CTC occupies 0x10 to 0x17
Next to work out what the 74LS138 enables. There seem to be some buffers and latches in the centre section of the board.
The clock source for both channels of this is the system clock, divided by 32. This gives a baud rate of 9600.