DESCRIPTION
Data present at the A inputs, along with the TCA control bit, is loaded into the A register on the rising edge of CLK. B data and the TCB control bit are similarly loaded. Loading of the A and B registers is controlled by the ENA and ENB controls. When HIGH, these controls prevent application of the clock to the respective register. The TCA and TCB controls specify the operands as two’s complement when HIGH, or unsigned magnitude when LOW. RND is loaded on the rising edge of CLK, providing either ENA or ENB are LOW. RND, when HIGH, adds ‘1’ to the most significant bit position of the least significant half of the product. Subsequent truncation of the 16 least significant bits produces a result correctly rounded to 16-bit precision. At the output, the Right Shift control (RS) selects either of two output formats. RS LOW produces a 31-bit product with a copy of the sign bit inserted in the MSB postion of the least significant half. RS HIGH gives a full 32-bit product. Two 16-bit output registers are provided to hold the most and least significant halves of the result (MSP and LSP) as defined by RS.
LOGIC Devices Incorporated
