Naming the first microprocessor

Naming the first microprocessor

When Federico Faggin designed the MCS-4 family he also christened the chips with distinct names: 4001, 4002, 4003, and 4004, breaking away from the numbering scheme used by Intel at that time which would have required the names 1302, 1105, 1507, and 1202 respectively. Had he followed Intel's number sequence, the idea that the chips were part of a family of components intended to work seamlessly together would have been lost[citation needed].

Intel's early numbering scheme for integrated circuits contemplated using a four-digit number for each component. The most significant digit position indicated the process technology used, as follows: The number "1" meant P-channel MOS, "2" indicated N-channel MOS, "3" was reserved for bipolar technology, and "5" was used for CMOS technology. No other numbers were used.

The next most significant digit was used to indicate the generic function performed by the component, as follows: "1" was used for RAM, "2" indicated random logic, "3" indicated ROM, "5" meant shift register, "6" and "7" were used for one-time programmable ROM and EPROM respectively. The last two digits of the number were used to indicate the sequential number in the development of the component.