Intel 8008 processors
Introduction: April 1972
In April 1972, Intel released the 8008 processor, which originally ran at a clock speed of 500KHz. The 8008 processor contained 3,500 transistors and was built on the same 10 micron process as the previous processor. The big change in the 8008 was that it had an 8-bit data bus, which meant it could move data 8 bits at a time - twice as much as the previous chip. It could also address more memory, up to 16KB. This chip was primarily used in dumb terminals and general-purpose calculators.
Source: Upgrading and Repairing PCs (13th Edition) by Scott Mueller.