UPD17P136ACT datasheet(90/292 Pages) NEC

90 / 292 page

CHAPTER 9 REGISTER FILE (RF)

9.2.3 Register File Manipulation Instructions

Reading and writing data from and to the register file is done using the window register (WR: address 78H) located

in the system register.

Reading and writing of data is performed using the following dedicated instructions:

PEEK WR, rf: Read the data in the address specified by rf and put it into WR.

POKE rf, WR: Write the data in WR into the address specified by rf.

Below is an example using the PEEK and POKE instructions.

Example

RF02

MEM0.82H

; Symbol definition

RF1F

MEM0.9FH

; Register file addresses 00H to 3FH must be defined with

RF53

MEM0.53H

; symbols as BANK0 addresses 80H to BFH.

RF6D

MEM0.6DH

; See 9.4 NOTES CONCERNING USE OF THE REGISTER FILE

RF70

MEM1.70H

; for details.

RF71

MEM1.71H

;

BANK0

PEEK

WR, RF02

;

POKE

RF1F, WR

;

PEEK

WR, RF53

;

POKE

RF6D, WR

;

BANK1

;

PEEK

WR, RF02

;

POKE

RF1F, WR

;

PEEK

WR, RF70

;

POKE

RF72, WR

;

Figure 9-3 shows an example of register file operation.

As shown in Figure 9-3, reading and writing of data to and from the control register (addresses 00H to 3FH) is

performed using the “PEEK WR, rf” and “POKE rf, WR” instructions. Data within the control register specified using

rf can be read from and written to the control register, only by using these instructions with the window register.

The fact that the register file overlaps with data memory in addresses 40H to 7FH has the following effect: When

a “PEEK WR, rf” or “POKE rf, WR” instruction is executed, the effect is the same as if they were being executed on

the data memory address (in the current bank) specified by rf.

Addresses 40H to 7FH of the register file can be operated by normal memory manipulation instructions.

UPD17P136ACT Datasheet(PDF) 90 Page - NEC

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