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Internally, the EDSAC used twos complement, binary numbers. These were either 17bit (one word) or 35bit (two words) long. Unusually, the multiplier was designed to treat numbers as fixedpoint fractions in the range 1 = x < 1, ie the binary point was immediately to the right of the sign. The accumulator could hold 71bits, including the sign, allowing two long (35bit) numbers to be multiplied without losing any precision. The instructions available were: add, subtract, multiply, collate, shift left, shift right, load multiplier register, store (and optionally clear) accumulator, conditional skip, read input tape, print character, round accumulator, noop and stop. There was no division instruction (though a number of division subroutines were available) and no way to directly load a number into the accumulator (a "store and zero accumulator" instruction followed by an "add" instruction were necessary for this). System softwareThe initial orders were hardwired on a set of uniselector switches and loaded into the low words of memory at startup. By September 1949, the initial orders had reached their final form and provided a primitive relocating assembler taking advantage of the mnemonic design described above, all in 41 words. Application softwareAn unusual feature of EDSAC was the availability of a substantial subroutine library. By 1951, 87 subroutines in the following categories were available for general use: floating point arithmetic; arithmetic operations on complex numbers; checking; division; exponentiation; routines relating to functions; differential equations; special functions; power series; logarithms; miscellaneous; print and layout; quadrature; read (input); nth root; Trigonometric functions; counting operations (simulating "repeat", "while" and "for" loops); vectors and matrices. Applications of EDSAC
Further developmentsEDSAC's successor, EDSAC 2, was commissioned in 1958. In 1961 an EDSAC 2 version of Autocode, an Algollike highlevel programming language for scientists and engineers, was developed by D. F. Hartley. In the mid60s, a successor to the EDSAC 2 was planned, but the move was instead made to the Titan, a prototype Atlas 2  the latter having been developed from the Atlas Computer of the University of Manchester, Ferranti, and Plessey. Resources 