Elliott 403 (WREDAC)

The Elliott 403, also known as WREDAC. This computer, designed for the Long Range Weapons Research Establishment in Australia, was a one-off project. It was larger and faster than the 402 by virtue of the following factors: (a). The Elliott 403 had a fast, four-word, instruction buffer so that decoding of a following instruction took place whilst the current instruction was being executed – (a form of pipelining). It also included a degree of look-ahead at branch instructions. (b). It had a comparatively large 512-word Immediate-Access store implemented as 12 single-word delay lines (effectively random-access) in the first sub-section, followed by 127 delay lines each of four words. (c). It had three visible index registers (B-lines), pre-selected by program from four sets held in the 12 fastest storage locations.