Editing Gate array (section)

=== Innovation ===
[[File:Timex Sinclair 1000 Motherboard BL (cropped Ferranti ULA).jpg|thumb|Ferranti {{abbr|ULA|Uncommitted Logic Array}} 2C210E on a [[Timex Sinclair 1000]] motherboard]]

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. CMOS technology was being driven by very low-power applications such as watch chips and battery-operated portable instrumentation, not performance. They were also well under the performance of the existing dominant logic technology, [[transistor–transistor logic]]. However, there were many niche applications where they were invaluable, particularly in low power, size reduction, portable and aerospace applications as well as time-to-market sensitive products. Even these small arrays could replace a board full of transistor–transistor logic gates if performance were not an issue. A common application was combining a number of smaller circuits that were supporting a larger LSI circuit on a board was affectionately known as "garbage collection". And the low cost of development and custom tooling made the technology available to the most modest budgets. Early gate arrays played a large part in the [[Citizens band radio#1970s popularity|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.

By the early 1980s, gate arrays were starting to move out of their niche applications to the general market. Several factors in technology and markets were converging. Size and performance were increasing; automation was maturing; the technology became "hot" when in 1981 IBM introduced its new flagship [[IBM 308X|3081]] mainframe with CPU comprising gate arrays. They were used in a consumer product, the ZX81, and new entrants to the market increased visibility and credibility.<ref>{{cite book |first=Chris |last=Smith |title=The ZX Spectrum ULA: How To Design A Microcomputer |publisher=ZX Design and Media |oclc=751703922 |date=2010 |isbn=9780956507105 |pages= |url=http://www.zxdesign.info/book/insideULA.shtml}}</ref><ref>{{cite web |title=Uncommitted IC logic |date=5 April 1980 |work=Design How-To |publisher=EDN |url=https://www.edn.com/uncommitted-ic-logic/}}</ref>

In 1981, [[Wilfred Corrigan]], Bill O'Meara, Rob Walker, and Mitchell "Mick" Bohn founded  [[LSI Corporation|LSI Logic]].<ref>{{Cite book|url=http://www.computerhistory.org/collections/catalog/102746194|title=LSI Logic oral history panel |publisher=Computer History Museum|date=30 November 2011 |access-date=2018-01-28}}</ref> Their initial intention was to commercialize emitter coupled logic gate arrays, but discovered the market was quickly moving towards CMOS. Instead, they licensed CDI's silicon gate CMOS line as a second source. This product established them in the market while they developed their own proprietary 5-micron 2-layer metal line. This latter product line was the first commercial gate array product amenable to full automation. LSI developed a suite of proprietary development tools that allowed users to design their own chip from their own facility by remote login to LSI Logic's system.

[[Sinclair Research]] ported an enhanced [[Sinclair ZX80|ZX80]] design to a ULA chip for the [[Sinclair ZX81|ZX81]], and later used a ULA in the [[ZX Spectrum]]. A compatible chip was made in Russia as T34VG1.<ref>[[:ru:Т34ВГ1|Т34ВГ1]] — article about the ZX Spectrum ULA compatible chip {{in lang|ru}}</ref>  [[Acorn Computers]] used several ULA chips in the [[BBC Micro]], and later a single ULA for the [[Acorn Electron]]. Many other manufacturers from the time of the [[home computer]] boom period used ULAs in their machines. The [[IBM PC]] took over much of the personal computer market, and the sales volumes made full-custom chips more economical. Commodore's Amiga series used gate arrays for the Gary and Gayle custom chips, as their code names may suggest.

In an attempt to reduce the costs and increase the accessibility of gate array design and production, Ferranti introduced in 1982 a computer-aided design tool for their uncommitted logic array (ULA) product called ULA Designer. Although costing £46,500 to acquire, this tool promised to deliver reduced costs of around £5,000 per design plus manufacturing costs of £1-2 per chip in high volumes, in contrast to the £15,000 design costs incurred by engaging Ferranti's services for the design process.<ref name="design198203_ferranti">{{ cite magazine | url=https://archive.org/details/sim_design_1982-03_399/page/n20/mode/1up | title=Make chips at home | magazine=Design | date=March 1982 | access-date=1 March 2022 | pages=17 }}</ref> 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. Verification of completed designs was performed by "external specialists" after the transfer of the design to a "CAD center" in Manchester, England or Sunnyvale, California, potentially over the telephone network. Prototyping completed designs took an estimated 3 to 4 weeks. The minicomputer itself was also adaptable to run as a laboratory or office system where appropriate.<ref name="dtic_ada352628">{{ cite magazine | url=https://archive.org/details/DTIC_ADA352658/page/n4/mode/1up | title=Ferranti Introduces CAD System for Gate Arrays | magazine=Wuerzburg Elektronikpraxis | date=February 1982 | access-date=1 March 2022 | issue=105 | pages=54 }}</ref>

Ferranti followed up on the ULA Designer with the Silicon Design System product based on the VAX-11/730 with 1&nbsp;MB of RAM, 120&nbsp;MB Winchester disk, and utilising a high-resolution display driven by a graphics unit with 500&nbsp;KB of its own memory for "high speed windowing, painting, and editing capabilities". The software itself was available separately for organisations already likely to be using VAX-11/780 systems to provide a multi-user environment, but the "standalone system" package of hardware and software was intended to provide a more affordable solution with a "faster response" during the design process. The suite of tools involved in the use of the product included logic entry and test schedule definition (using Ferranti's own description languages), logic simulation, layout definition and checking, and mask generation for prototype gate arrays. The system also sought to support completely auto-routed designs, utilising architectural features of Ferranti's auto-routable (AR) arrays to deliver a "100-percent success auto-layout system" with this convenience incurring an increase in silicon area of approximately 25 percent. <ref name="computerdesign198403_ferranti">{{ cite magazine | url=https://archive.org/details/bitsavers_computerDe_409597766/page/197/mode/1up | title=Automation Cuts Design Time for Gate Arrays | magazine=Computer Design | date=March 1984 | access-date=1 March 2022 | last1=Walker | first1=Anthony V. | pages=197-198,200,202,204 }}</ref>

Other British companies developed products for gate array design and fabrication. 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,<ref name="electronicbusiness19861015_trends">{{ cite magazine | url=https://archive.org/details/sim_electronic-business_1986-10-15_12_20/page/46/mode/1up | title=An emerging market for British engineering tools | magazine=Electronic Business | date=15 October 1986 | access-date=2 March 2022 | last1=Coffey | first1=Margaret | pages=46,48 }}</ref> etching designs onto Ferranti ULA devices that formed the physical basis of these custom chips. Typical prototype production costs were stated as £100 per chip.<ref name="acornuser198604_qudos">{{ cite news | url=https://archive.org/details/AcornUser045-Apr86/page/n16/mode/1up | title=Universities choose chip design on Beeb | work=Acorn User | date=April 1986 | accessdate=10 October 2020 | pages=15 }}</ref> Quickchip was subsequently ported to the [[Acorn Cambridge Workstation]], with a low-end version for the [[BBC Micro]],<ref name="acornuser198609_qudos">{{ cite news | url=https://archive.org/details/AcornUser050-Sep86/page/n8/mode/1up | title=News in brief | work=Acorn User | date=September 1986 | accessdate=10 October 2020 | pages=7 }}</ref> and to the [[Acorn Archimedes]].<ref name="acorn_app155">{{ cite book | url=http://www.4corn.co.uk/archive/docs/AMPAPP/150/APP155%20(1st%20ed)%20-%20(1988)-opt.pdf | title=Hardware expansion and software applications for the Archimedes system | publisher=Acorn Computers Limited | date=September 1988 | issue=1 | access-date=25 April 2021 | pages=22 }}</ref>