UPD17P136ACT datasheet(74/292 Pages) NEC

74 / 292 page

CHAPTER 7 SYSTEM REGISTER (SYSREG)

Example 2. Indirect data transfer using the general register (Execution of “MOV @r, m”)

R005 MEM

0.05H

M034 MEM

0.34H

MOV

IXL, #0001B

; Column address

← 5 (OR of 4 and 1)

MOV

IXM, #0000B

; Row address

← 3 (OR of 3 and 0)

MOV

IXH, #0000B

; MPE

← 0, bank ← 0 (OR of 0 and 0)

PSW, #.DF.IXE AND 0FH ; IXE

← 1

MOV

R005, #8

; R005

← 8 (Setting column address of @r)

MOV

@R005, M034

; Indirect data transfer using the register

; (0.38H)

← (0.35H)

As shown in Figure 7-13, when the above instructions are executed, the contents of data memory

address 35H is transferred to data memory location 38H.

When the MOV @r, m instruction is executed when IXE = 1, the data memory address specified

by m (direct address) is modified using the contents of the index register. The bank and row address

of the indirect address specified by @r are also modified using the index register.

The bank, row address, and column address specified by m (direct address) are all modified, and

the bank and row address specified by @r (indirect address) are modified.

Therefore, in the above example the direct address is 35H and the indirect address is 38H.

This example is different from Example 3 in 7.5.3 when IXE = 0 for the following reasons: In this

example, the bank, row address and column address of the direct address specified by m are

modified using the index register. The general register is transferred to the address specified by

the column address of the modified data memory address and the same row address. (In Example

3 in 7.5.3, the direct address is not modified.)

Figure 7-13. Operation Example When IXE = 1 and MPE = 0

0123456789

Column address

System register

General

R005

Example 2.

MOV @R005, M034

00000110100B

00000000001B

00000110101B

Column address specified

as transfer destination

M034

Direct

address

Index modification

Indirect address

OR)

Real address

M034

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