| 摘要 |
PURPOSE:To perform function arithmetic at a high speed through even algorithm which does not include division, by providing an address arithmetic circuit with a function of generating an address to an initial value table at a high speed. CONSTITUTION:An address arithmetic part consists of a two-port register 50, arithmetic logical circuit ALU53, and shifter 54. Ports A and B of the register 50 are both used for reading, but only the port B is used for writing. A three- input one-output selector 56 selects one of the data output of the ALU53, shifter 54, and a bus 16 as write data to the register 50. For this purpose, while a one-bit write request signal WE is present, a four-bit address signal ADRB is supplied from a microprogram and then the data is written in the address. When the reading is performed through the port B, on the other hand, the signal ADRB is supplied while the signal WE is not present. Further, the signal ADRA is only supplied for the reading of the port A. |
