[[File:Intel 8080 open-closed.jpg|thumb|right|Intel 8080]]
[[File:KL Intel C8008-1.jpg|thumb|right|Intel 8008]]
The '''Intel 8080''' is a seminal CPU introduced in 1974 that gave rise to the personal computer/home computer/microcomputer revolution.
A full instruction cycle requires anywhere from 4 to 18 states for its completion, depending on the kind of instruction involved.
{| class="wikitable"|+ T-state Definitions|-! T-state !! Description|-| T1| A memory address or I/O device number is placed on the Address Bus (A<sub>15-0</sub>); status information is placed on Data Bus (D<sub>7-0</sub>).|-| T2| The CPU samples the READY and HOLD inputs and checks for halt instruction.|-| TW (optional)| Processor enters wait state if READY is low or if HALT instruction has been executed.|-| T3| An instruction byte (FETCH machine cycle), data byte (MEMORY READ, STACK READ) or interrupt instruction (INTERRUPT machine cycle) is input to the CPU from the Data Bus; or a data byte (MEMORY WRITE, STACK WRITE or OUTPUT machine cycle) is output onto the data bus.|-| T4, T5 (optional) | States T4 and T5 are available if the execution of a particular instruction requires them; if not, the CPU may skip one or both of them. T4 and T5 are only used for internal processor operations.|} See this [[Media:Intel 8080 details.pdf|Intel 8080 document]], containing a detailed breakdown of machine M-cycles and T-states.
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