UPD17P136ACT datasheet(70/292 Pages) NEC

70 / 292 page

CHAPTER 7 SYSTEM REGISTER (SYSREG)

7.5.4 IXE = 0 and MPE = 1 (Diagonal Indirect Data Transfer)

As shown in Figure 7-9, the indirect data transfer bank and row address specified by @r become the data memory

row address pointer value only when general register indirect data transfer instructions (MOV @r, m and MOV m, @r)

are used.

Example 1. Execution of “MOV @r, m” when the general register is in row address 0

R005 MEM

0.05H

M034 MEM

0.34H

MOV

MPL, #0110B

; MP

← 6 (Setting row address of @r)

MOV

MPH, #1000B

; MPE

← 1, bank ← 0

MOV

R005, #8

; R005

← 8 (Setting column address of @r)

MOV

@R005, M034

; Indirect transfer of data in the register (0.68H)

← (0.34H)

As shown in Figure 7-11, when the above instructions are executed, the contents of data memory

address M034 is transferred to data memory location 68H.

When the MOV @r, m instruction is executed when MPE = 1, the contents of the data memory

address specified by m is transferred to the column address pointed to by the row address @r being

pointed to by the memory pointer.

In this case, the indirect address specified by @r becomes the value used for the bank and row

address data memory pointer (above example uses row address 6). The column address is the value

in the general register address specified by r (above example uses column address 8).

Therefore the address in the above example is 68H.

This example is different from Example 2 in 7.5.3 when MPE = 0 for the following reasons: In this

example, the data memory row address pointer is used to point to the indirect address bank and

row address specified by @r. (In Example 2 in 7.5.3, the indirect address bank and row address

are the same as m.)

By setting MPE = 1, diagonal indirect data transfer can be performed using the general register.

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