Zilog Z80

What's a Z80 doing here? Primarily I collect x86 CPU's, however, I came across a nice Z80 CPU and since the Z80 had a significant impact on the market I added it to my collection.

The Z80 is a CPU designed in the mid 70'ies. It was compatible with the Intel 8080 but featured several improvements as well. It became the heart for many systems like ZX Spectrum, SEGA Master System (and Mega Drive/Genesis), TRS-80 and also in various portable computers, early game arcade systems and in calculators like the TI-81 and newer.