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Four-Phase Systems AL1
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Four-Phase Systems AL1
The AL1 was an early 8-bit microprocessor slice designed by Four-Phase Systems and unveiled in February 1970. The chip was first used as part of Four-Phase's System IV/70 24-bit minicomputer to be used with terminals shipped in January 1971. It has been widely reported as one of the first microprocessor central processing units (CPU) publicly disseminated, pre-dating the Intel 4004 by one year. In modern terms, the AL1 is a bit-slice design. The company never advertised the AL1 as an independent product and did not sell it to other customers; the 4004 was the first such design to be sold in standalone form. The AL1 was later updated as the AL4.
The AL1 served as a key example of prior art in a series of patent lawsuits initiated by Texas Instruments and Gilbert Hyatt regarding the basic technology of the microprocessor. Lee Boysel demonstrated the function of the AL1 in court to demonstrate that the design incorporated all of the patented concepts on a chip completed prior to either party's claim.
Lee Boysel started work at Fairchild Semiconductor in 1966 after working at several other company's semiconductor departments. At Fairchild he worked on MOS design, which at that time was a very new concept. Over the next two years he developed several new MOS chips, including a 256-bit static RAM, an 8-bit adder, and the first integrated circuit with over 100 gates.
The adder, the Fairchild 3800, was the first device that would today be known as an 8-bit arithmetic logic unit, or ALU. It was, however, incomplete by modern standards, as it included only the arithmetic operations and lacked the logic operations like AND and bit-shifting. It did, however, include an internal accumulator, which it used to produce results without needing to store intermediate steps in external memory. Similar designs would soon appear from other companies, notably Texas Instruments' 74181 which was a complete 4-bit ALU in only 63 gates.
Through this period, Boysel was working on different ways to lay out MOS circuity using the four-phase logic concept that he was developing. This is a way to lay out the individual transistors that make up a logic gate, and the way the clock generator sends the signals through these transistors. Using this concept, the circuits can be smaller than the transistor-transistor logic (TTL) design concepts being used previously, and a larger number of gates can fit on a single chip. He began the design of a greatly expanded IC with around 1,000 gates using this process.
Boysel left Fairchild in October 1968 to start his own company, Four-Phase Systems, which incorporated in February 1969. Corning Glass, who was at that time investing in the emerging semiconductor market, provided start-up funding of $2 million. Four-Phase was what would today be known as a fabless designer, using another Fairchild spin-off, Cartesian, as a semiconductor foundry. Smaller gates translates to cheaper ICs, which he intended to use to build lower-cost computers that would compete with systems from Data General and the mid-range machines from IBM.
The first engineering samples of the AL1 were made available in 1970. Three AL1s were combined with three custom read only memory (ROM) chips, three random logic chips, and an external clock generator onto a board to produce the 24-bit CPU for the System IV/70, which could power up to 32 video display terminals. The company never sold the AL1 or the complete processor boards, nor did they file patents on the design, but they did publish an article in the April 1970 issue of Computer Design magazine describing it and how it could be used to build a simple computer.
The IV/70 was successful; by the mid-1970s they had sold 350 systems. When sales of the AL1-based systems dwindled by the late 1970s, the firm introduced a series of Unix-based computers based on the Motorola 68000, which led to Motorola purchasing the company in 1982.
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Four-Phase Systems AL1 AI simulator
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Four-Phase Systems AL1
The AL1 was an early 8-bit microprocessor slice designed by Four-Phase Systems and unveiled in February 1970. The chip was first used as part of Four-Phase's System IV/70 24-bit minicomputer to be used with terminals shipped in January 1971. It has been widely reported as one of the first microprocessor central processing units (CPU) publicly disseminated, pre-dating the Intel 4004 by one year. In modern terms, the AL1 is a bit-slice design. The company never advertised the AL1 as an independent product and did not sell it to other customers; the 4004 was the first such design to be sold in standalone form. The AL1 was later updated as the AL4.
The AL1 served as a key example of prior art in a series of patent lawsuits initiated by Texas Instruments and Gilbert Hyatt regarding the basic technology of the microprocessor. Lee Boysel demonstrated the function of the AL1 in court to demonstrate that the design incorporated all of the patented concepts on a chip completed prior to either party's claim.
Lee Boysel started work at Fairchild Semiconductor in 1966 after working at several other company's semiconductor departments. At Fairchild he worked on MOS design, which at that time was a very new concept. Over the next two years he developed several new MOS chips, including a 256-bit static RAM, an 8-bit adder, and the first integrated circuit with over 100 gates.
The adder, the Fairchild 3800, was the first device that would today be known as an 8-bit arithmetic logic unit, or ALU. It was, however, incomplete by modern standards, as it included only the arithmetic operations and lacked the logic operations like AND and bit-shifting. It did, however, include an internal accumulator, which it used to produce results without needing to store intermediate steps in external memory. Similar designs would soon appear from other companies, notably Texas Instruments' 74181 which was a complete 4-bit ALU in only 63 gates.
Through this period, Boysel was working on different ways to lay out MOS circuity using the four-phase logic concept that he was developing. This is a way to lay out the individual transistors that make up a logic gate, and the way the clock generator sends the signals through these transistors. Using this concept, the circuits can be smaller than the transistor-transistor logic (TTL) design concepts being used previously, and a larger number of gates can fit on a single chip. He began the design of a greatly expanded IC with around 1,000 gates using this process.
Boysel left Fairchild in October 1968 to start his own company, Four-Phase Systems, which incorporated in February 1969. Corning Glass, who was at that time investing in the emerging semiconductor market, provided start-up funding of $2 million. Four-Phase was what would today be known as a fabless designer, using another Fairchild spin-off, Cartesian, as a semiconductor foundry. Smaller gates translates to cheaper ICs, which he intended to use to build lower-cost computers that would compete with systems from Data General and the mid-range machines from IBM.
The first engineering samples of the AL1 were made available in 1970. Three AL1s were combined with three custom read only memory (ROM) chips, three random logic chips, and an external clock generator onto a board to produce the 24-bit CPU for the System IV/70, which could power up to 32 video display terminals. The company never sold the AL1 or the complete processor boards, nor did they file patents on the design, but they did publish an article in the April 1970 issue of Computer Design magazine describing it and how it could be used to build a simple computer.
The IV/70 was successful; by the mid-1970s they had sold 350 systems. When sales of the AL1-based systems dwindled by the late 1970s, the firm introduced a series of Unix-based computers based on the Motorola 68000, which led to Motorola purchasing the company in 1982.