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Definition: Intel 4004
The first microprocessor. Designed by Marcian E. "Ted" Hoff at Intel in 1971, the 4004 was a 4-bit, general-purpose CPU initially developed for the Japanese Busicom calculator. Running at a clock rate of 740 kHz, the 4004 could address 4KB of read-only memory (ROM) to hold the program and 640 bytes of RAM to store the input and computed results.
A Small But Great Start
Given the tiny amount of RAM in the 4004, it was limited. Nevertheless, the 4004 was the beginning of a long line of microprocessors from Intel. The 4040 successor to the 4004 added interrupts, 24 index registers (up from 16) and a second 4KB program bank.
Why Not Make It General Purpose
Instead of going through the effort of designing a chip that could only be used for a calculator, Hoff made a general-purpose processor that executed a calculator program, but like a computer, could be used for anything else. In the early 1970s, computer CPUs were the size of a refrigerator and cost hundreds of thousands of dollars. Thus began the new world of general-purpose CPUs on a chip, and since then, billions have been produced (see microprocessor and microcontroller).
The 4004 CPU
The 4004-Based Busicom Calculator
A Half Century of Progress
A Small But Great Start
Given the tiny amount of RAM in the 4004, it was limited. Nevertheless, the 4004 was the beginning of a long line of microprocessors from Intel. The 4040 successor to the 4004 added interrupts, 24 index registers (up from 16) and a second 4KB program bank.
Why Not Make It General Purpose
Instead of going through the effort of designing a chip that could only be used for a calculator, Hoff made a general-purpose processor that executed a calculator program, but like a computer, could be used for anything else. In the early 1970s, computer CPUs were the size of a refrigerator and cost hundreds of thousands of dollars. Thus began the new world of general-purpose CPUs on a chip, and since then, billions have been produced (see microprocessor and microcontroller).
With only 2,300 transistors, the general-purpose 4004 launched Intel into the microprocessor business. (Image courtesy of Intel Corporation.)
The product that inspired Ted Hoff to create the 4004. (Image courtesy of AUCTION TEAM BREKER, Cologne, Germany, (c) 2013.)
Intel microprocessors today have a million times more transistors than Hoff's 4004. For example, this i9 CPU contains nearly three billion transistors compared to 2,300. (Image courtesy of Intel Corporation.)
FIFTY YEAR COMPARISON
OF INTEL CPU CHIPS
4004 Core
(1971) (2021)
Number of
transistors 2,300 approx 3 billion
Register size
(bits) 4 64
Clock speed 750 kHz 5.2 GHz
Cores 1 16
Threads 1 24
Wafer size
(inches) 2 11.8
Node size (nm) 10,000 10