Abstract: A data processing system is provided including an arithmetic logic unit 20, 22, 24 receiving input operands from M X-bit registers to produce output data words stored within N Y-bit registers, where M/N=3, 8.ltoreq.Y-X.ltoreq.16 and 3X=2Y. This arrangement is particularly suited for digital signal processing and in situations where each input operand is used a plurality of times before a new input operand is loaded in its place in a register.

Abstract: A data processing system having a plurality of registers 10 and an arithmetic logic unit 20, 22, 24 is responsive to program instruction words. At least one program instruction word includes a destination register bit field <dest> specifying a destination register of a result data word and a destination register write disable flag for disabling writing of that result data word to the destination register.

Abstract: A data processing system having a plurality of registers 10 and an arithmetic logic unit 20, 22, 24 includes program instruction words having a source register bit field Sn specifying one of the registers storing an input operand data word together with an input operand size flag indicating whether the input operand has an N-bit size or (N/2)-bit size together with a high/low location flag indicating which of the high order bit positions or low order bit positions stores the input operand if it is of the smaller size. It is preferred that the arithmetic logic unit is also able to perform parallel operation program instruction words operating independently upon (N/2)-bit input operand data words stored in respective halves of a register.

Abstract: A digital signal processing system is described in which a microprocessor unit 2 operating under control of microprocessor program instruction words controls data transfer to and from a data storage device 8 and the supply and fetching of data to and from a digital signal processing unit 4.

Abstract: A data processing system incorporating an arithmetic logic unit 20, 22, 24 having an N-bit data pathway and supporting parallel operation program instruction words in which to independent arithmetic operations are carried out in parallel by the arithmetic logic unit upon (N/2)-bit input operand words. Two sets of condition code flags N, Z, C V, SN, SZ, SC, SV responsive to the separate arithmetic logic operations are provided.