Four-Phase Systems AL1

The AL1 was an early 8-bit microprocessor designed by Four-Phase Systems and first run in April 1969. It is the first single-chip central processing unit (CPU) to be produced,^[1][b] pre-dating the Intel 4004 by two years. Although it could be used as a stand-alone general purpose CPU, Four-Phase did not use it in this fashion at the time. Instead, they used three AL1's in a bit-slice system to produce a 24-bit minicomputer, the System IV/70. The company never advertised the AL1 as a product and did not sell it to other customers, the 4004 was the first design to be sold in standalone form.

In 1990, Texas Instruments began to enforce patents on the basic concept of a microprocessor, which they had initially filed in 1971. These plans were upset when a patent was granted to another designer, Gilbert Hyatt. The resulting flurry of lawsuits led to the AL1 becoming famous in 1995 when Lee Boysel built a small computer to demonstrate his design incorporated all of these concepts using a chip manufactured two years before TI's design and a year before Hyatt's.^[c]

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