Depending on how you delineate the families, the origins of x86 date back to 1972 (Intel 8008) and obviously x86 itself dates to 1978 ;) Z80 also dates back a

Depending on how you delineate the families, the origins of x86 date back to 1972 (Intel 8008) and obviously x86 itself dates to 1978 ;) Z80 also dates back a really long time, and there is a ton of stuff that still uses Z80-family processors in many embedded applications (microwaves, calculators, etc). I realize neither of those are probably the absolute oldest, but this is going to hinge on what each commenter's exact definition of "families" and "still in use" are. Active development/new chips being released? Still in widespread legacy use? One-off legacy systems still hanging on in an industrial installation somewhere? In terms of what is the absolute oldest - again depending on your exact definition of "family", z/System is arguably the oldest computer family, you can trace a direct lineage back to punchcard tabulation programs, which date back into the 1880s. z/OS systems can run programs originally compiled for System/360, which was designed to be directly ported from plugboard programs for programmable tabulators, so in a "ship of theseus" sense that is likely the oldest computer family.