UPD17015 datasheet(25/120 Pages) NEC

25 / 120 page

µPD17015

6. GENERAL-PURPOSE REGISTER (GR)

6.1

OUTLINE OF GENERAL-PURPOSE REGISTER

Fig. 6-1 outlines the general-purpose register.

For the

µPD17015, the general-purpose register is fixed to low address 0 of the data memory, consisting of 16

nibbles (00H to 0FH, 16

× 4 bits).

16 nibbles of the row address 0 specified as a general-purpose register is used to perform an operation with or

transfer data to and from the data memory.

This means that an operation or data transfer between data memory areas can be performed with one instruction.

As with other data memory areas, a general-purpose register can be controlled using data memory manipulation

instructions.

Fig. 6-1 Outline of General-Purpose Register

012

Column address

Transfer,

operation

Data memory

System register

General-purpose register

6.2

GENERAL-PURPOSE REGISTER ADDRESS GENERATION WITH INSTRUCTIONS

Sections 6.2.1 and 6.2.2 below describe general-purpose register address generation when each instruction is

executed.

For the detailed operation of each instruction, see Chapter 7.

6.2.1

Addition Instructions (ADD r,m, ADDC r,m)

Subtraction Instructions (SUB r,m, SUBC r,m)

Logical Operation Instructions (AND r,m, OR r,m, XOR r,m)

Direct Transfer Instructions (LD r,m, ST m,r), and

Rotate Instruction (RORC r)

Fig. 6-2 indicates a general-purpose register address R specified by operand r of an instruction. Operand r specifies

only a column address.

UPD17015 Datasheet(PDF) 25 Page - NEC