Fun fact: an Amstrad CPC equipped with a 4MB RAM expansion has 32 million transistors dedicated to RAM while the Z80 CPU still has only 8500 transistors.
The Z80 is mid-1970s technology while the 64KB DRAM is early-1980s technology and the 4MB DRAM is early-1990s technology.
The Z80 comes in a 40-pin DIP package. It has been manufactured in A, B, and C models, differing only in maximum clock speed. It also has been manufactured as a stand-alone microcontroller with various configurations of on-chip RAM and EPROM.