The Ferranti 9RK020-3F programmable gate array is a poorly documented device. Not much is known about this chip, other than it is part of Ferranti's line of ULA 'Uncommitted Logic Array' integrated circuits. Ferranti ULA chips saw use in a number of noteworthy computer products from the 1980s, including the Timex Sinclair ZX81 and ZX Spectrum. The 9RK020 is probably most closely related to the 12C021M, a 12 tile programmable array used in the Acorn Electron home computer. The manufacturers of the Acorn Electron relocated nearly all of the computer's support logic into a 12C021M array, resulting in a 90 percent reduction of the Electron's total chip count. The complexity of this ULA caused significant disruption to the Electron's 1983 launch however, resulting in delays and manufacturing shortages as Ferranti struggled to ramp up production of the complicated device.
The Ferranti 9RK020-3F is packaged in a ceramic leadless carrier similar in size and shape to the ULA used in the Acorn Electron. The 9RK020-3F is not leadless however; long gold pins have been brazed to the pads on the carrier, converting it into a surface mount flatpack. We suspect the 9RK020 is a 9 tile device, but it's specifications are otherwise unknown.
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