Ken Shirriff on Twitter: "The Zilog Z80 processor (1976) was a key competitor to the 6502. The Z80 was used in computers such as the Radio Shack TRS-80, the ZX Spectrum, the "
![File:Basic Measuring Instruments - Math Processor 83002190 - Zilog Z80 CTC Z84C3008PEC-3918.jpg - Wikimedia Commons File:Basic Measuring Instruments - Math Processor 83002190 - Zilog Z80 CTC Z84C3008PEC-3918.jpg - Wikimedia Commons](https://upload.wikimedia.org/wikipedia/commons/0/05/Basic_Measuring_Instruments_-_Math_Processor_83002190_-_Zilog_Z80_CTC_Z84C3008PEC-3918.jpg)
File:Basic Measuring Instruments - Math Processor 83002190 - Zilog Z80 CTC Z84C3008PEC-3918.jpg - Wikimedia Commons
![File:Basic Measuring Instruments - Math Processor 83002190 - Zilog Z80 SIO Z84C4008PEC-3920.jpg - Wikimedia Commons File:Basic Measuring Instruments - Math Processor 83002190 - Zilog Z80 SIO Z84C4008PEC-3920.jpg - Wikimedia Commons](https://upload.wikimedia.org/wikipedia/commons/5/52/Basic_Measuring_Instruments_-_Math_Processor_83002190_-_Zilog_Z80_SIO_Z84C4008PEC-3920.jpg)