Intel 4040 processors
Introduction: 1974
The 4040 is an enhanced follow-on processor to the Intel 4004.
The 4040 was used primarily in games, test, development, and control equipment. The package of the 4040 is more than twice as wide as the 4004 and has 24 pins vs. the 16 of the 4004. The 4040 added 14 instructions, larger stack, 8KB program space, 8 more registers, and interrupt abilities (including shadows of the first 8 registers).
Source: Wikipedia, the free encyclopedia.