D17133CS datasheet(220/289 Pages) NEC

220 / 289 page

CHAPTER 18

INSTRUCTION SET

205

(2)

SUB m, #n4

Subtract immediate data from data memory

<1> OP code

10001

<2> Function

When CMP=0, (m)

← (m) – n4

Subtracts immediate data from the data memory contents, and stores the result in data memory.

When CMP=0, (m) – n4

The result is not stored in data memory. Carry flag CY and zero flag Z are changed, according to the result.

Sets carry flag CY, if a borrow occurs as a result of the subtraction. Resets the carry flag CY, if no borrow

occurs.

If the subtraction result is other than zero, zero flag Z is reset, regardless of compare flag CMP.

If the subtraction result is zero, with the compare flag reset (CMP=0), the zero flag Z is set.

If the subtraction result is zero, with the compare flag set (CMP=1), the zero flag Z is not changed.

Subtraction can be executed in binary 4-bit or BCD. The BCD flag for program status word PSWORD specifies

which kind of subtraction is to be executed.

<3> Example 1

Subtracts 5 from the address 0.2FH contents, and stores the result in address 0.2FH:

(0.2FH)

← (0.2FH) – 5

MEM02F

MEM

0.2FH

SUB

MEM02F, #05H

Example 2

To subtract 5 from the address 0.6FH contents and store the result in address 0.6FH. At this time, data

memory address 0.6FH can be specified by selecting data memory address 2FH, if IXE=1, IXH=0, IXM=4,

and IXL=0, i.e., IX=0.40H.

D17133CS Datasheet(PDF) 220 Page - NEC