Part number	Datasheet
Farnell: 1081892	no longer stocked
Mouser: 692-Z84C2008PEG	Zilog, Z84C20
RS: 625-8952	Zilog, Z84C20

The above part is rated at a clock speed of 8 MHz but a faster part, such as the 10MHz part shown below, can be used instead.

Part number	Datasheet
Farnell: ?	no longer stocked
Mouser: 692-Z84C2010PEG	Zilog, Z84C20
RS: n/a	n/a

Further information can be found in the Z80 CPU Peripherals User Manual – Zilog – UM0081