UPD77112GC datasheet(21/80 Pages) NEC

21 / 80 page

Data Sheet U12801EJ4V0DS00

µµµµPD77110, 77111, 77112

2.2 Arithmetic Unit

This unit performs multiplication, addition, logical operations, and shift, and consists of a 40-bit multiply

accumulator, 40-bit data ALU, 40-bit barrel shifter, and eight 40-bit general-purpose registers.

2.2.1 General-purpose registers (R0 through R7)

These eight 40-bit registers are used to input/output data for arithmetic operations, and load or store data from/to

data memory.

A general-purpose register (R0 to R7) is made up of three parts: R0L through R7L (bits 15 through 0), R0H

through R7H (bits 31 through 16), and R0E through R7E (bits 39 through 32). Depending on the type of operation,

RnL, RnH, and RnE are used as one register or in different combinations.

2.2.2 Multiply accumulator (MAC)

The MAC multiplies two 16-bit values, and adds or subtracts the multiplication result from one 40-bit value, and

outputs a 40-bit value.

The MAC is provided with a shifter (MSFT: MAC ShiFTer) at the stage preceding the input stage. This shifter can

arithmetically shift the 40-bit value to be added to or subtracted from the multiplication result 1 or 16 bits to the right .

2.2.3 Arithmetic logic unit (ALU)

This unit inputs one or two 40-bit values, executes an arithmetic or logical operation, and outputs a 40-bit value.

2.2.4 Barrel shifter (BSFT: Barrel ShiFTer)

The barrel shifter inputs a 40-bit value, shifts it to the left or right by any number of bits, and outputs a 40-bit value.

The data may be arithmetically shifted to the right shifted to the right, in which case the data is sign-extended, or

logically shifted to the right, in which case 0 is inserted from the MSB.

UPD77112GC Datasheet(PDF) 21 Page - NEC