UPD17015GS datasheet(28/120 Pages) NEC

28 / 120 page

µPD17015

7.2

CONFIGURATION AND FUNCTIONS OF THE COMPONENTS OF THE ALU BLOCK

7.2.1

ALU

In response to a programmed instruction, the ALU performs 4-bit arithmetic or logic processing, bit discrimination,

comparative discrimination, rotation, or transfer.

7.2.2

Temporary Storage Registers A and B

Temporary storage registers A and B temporarily hold the 4-bit data.

These registers are automatically used when an instruction is executed. They cannot be controlled by a program.

7.2.3

Program Status Word

A program status word controls the operation of the ALU and holds the status of the ALU.

For details of the program status word, see Section 5.2.

7.2.4

Decimal Conversion Circuit

If the BCD flag of the program status word is set to 1 when an arithmetic operation is executed, the decimal

conversion circuit converts the results of the arithmetic operation to a decimal number.

7.2.5

Address Controller

The address controller specifies an address in data memory.

7.3

ALU OPERATIONS

Table 7-1 lists the operations performed by the ALU when instructions are executed.

Table 7-2 lists the converted decimal data used in decimal operations.

UPD17015GS Datasheet(PDF) 28 Page - NEC