Gate array
[6] IBM developed proprietary bipolar master slices that it used in mainframe manufacturing in the late 1970s and early 1980s, but never commercialized them externally.
The first CMOS gate arrays were developed by Robert Lipp[8][9] in 1974 for International Microcircuits, Inc.[7] (IMI) a Sunnyvale photo-mask shop started by Frank Deverse, Jim Tuttle and Charlie Allen, ex-IBM employees.
The most important were: the strict organization of n-channel and p-channel transistors in 2-3 row pairs across the chip; and running all interconnect on grids rather than minimum custom spacing, which had been the standard until then.
Chips at the time were designed by hand, drawing all components and interconnecting on precision gridded Mylar sheets, using colored pencils to delineate each processing layer.
After a falling out with IMI, Robert Lipp went on to start California Devices, Inc. (CDI) in 1978 with two silent partners, Bernie Aronson, and Brian Tighe.
A couple of years later, CDI followed up with "channel-less" gate arrays that reduced the row blockages caused by a more complex silicon underlayer that pre-wired the individual transistor connections to locations needed for common logic functions, simplifying the first-level metal interconnect.
[8] Early gate arrays were low-performance and relatively large and expensive compared to state-of-the-art n-MOS technology then being used for custom chips.
Early gate arrays played a large part in the CB craze in the 1970s as well as a vehicle for the introduction of other later mass-produced products such as modems and cell phones.
Size and performance were increasing; automation was maturing; the technology became "hot" when in 1981 IBM introduced its new flagship 3081 mainframe with CPU comprising gate arrays.
[10][11] In 1981, Wilfred Corrigan, Bill O'Meara, Rob Walker, and Mitchell "Mick" Bohn founded LSI Logic.
[12] Their initial intention was to commercialize emitter coupled logic gate arrays, but discovered the market was quickly moving towards CMOS.
Commodore's Amiga series used gate arrays for the Gary and Gayle custom chips, as their code names may suggest.
[14] Based on a PDP-11/23 minicomputer running RSX/11M, together with graphical display, keyboard, "digitalizing board", control desk and optional plotter, the solution aimed to satisfy the design needs of gate arrays from 100 to 10,000 gates, with the design being undertaken entirely by the organisation acquiring the solution, starting with a "logic plan", proceeding through the layout of the logic in the gate array itself, and concluding with the definition of a test specification for verification of the logic and for establishing an automated testing regime.
[15] Ferranti followed up on the ULA Designer with the Silicon Design System product based on the VAX-11/730 with 1 MB of RAM, 120 MB Winchester disk, and utilising a high-resolution display driven by a graphics unit with 500 KB of its own memory for "high speed windowing, painting, and editing capabilities".
Qudos Limited, a spin-off from Cambridge University, offered a chip design product called Quickchip available for VAX and MicroVAX II systems and as a complete $11,000 turnkey solution, providing a suite of tools broadly similar to those of Ferranti's products including automatic layout, routing, rule checking and simulation functionality for the design of gate arrays.
Qudos employed electron beam lithography,[17] etching designs onto Ferranti ULA devices that formed the physical basis of these custom chips.
Xilinx was founded in 1984, and its first products were much like early gate arrays, slow and expensive, fit only for some niche markets.
Fabless companies such as LSI Logic and CDI survived on selling design services and computer time rather than on production revenues.
[8] As of the early 21st century, the gate array market was a remnant of its former self, driven by the FPGA conversions done for cost or performance reasons.
Since requirements vary, gate arrays usually come in families, with larger members having more of all resources, but correspondingly more expensive.
Gate arrays were used widely in the home computers in the early to mid 1980s, including in the ZX81, ZX Spectrum, BBC Micro, Acorn Electron, Advance 86, and Commodore Amiga.
In the 1980s, the Forth Novix N4016 and HP 3000 Series 37 CPUs, both stack machines were implemented by gate arrays as were some graphic terminal functions.
