SM89516B datasheet(23/49 Pages) SYNCMOS

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SM89516B

8-Bit Micro-controller

64KB Flash

& 1KB RAM embedded

Specifications subject to change without notice contact your sales representatives for the most recent information.

ISSFD-M087

Ver D SM89516B 08/07/2015

- 23 -

4.3

Program Status Word

Mnemonic: PSW

Address: D0h

Reset

RS [1:0]

00h

CY: Carry flag.

AC: Auxiliary Carry flag for BCD operations.

F0: General purpose Flag 0 available for user.

RS[1:0]: Register bank select, used to select working register bank.

RS[1:0]

Bank Selected

Location

Bank 0

00h – 07h

Bank 1

08h – 0Fh

Bank 2

10h – 17h

Bank 3

18h – 1Fh

OV: Overflow flag.

F1: General purpose Flag 1 available for user.

P: Parity flag, affected by hardware to indicate odd/even number of “one” bits in the

Accumulator, i.e. even parity.

4.4

Stack Pointer

The stack pointer is a 1-byte register initialized to 07h after reset. This register is incremented before PUSH and

CALL instructions, causing the stack to start from location 08h.

Mnemonic: SP

Address: 81h

Reset

SP [7:0]

07h

SP[7:0]: The Stack Pointer stores the scratchpad RAM address where the stack begins. In other

words, it always points to the top of the stack.

4.5

Data Pointer

The data pointer (DPTR) is 2-bytes wide. The lower part is DPL, and the highest is DPH. It can be loaded as a 2-

byte register (e.g. MOV DPTR, #data16) or as two separate registers (e.g. MOV DPL,#data8). It is generally used

to access the external code or data space (e.g. MOVC A,@A+DPTR or MOVX A,@DPTR respectively).

Mnemonic: DPL

Address: 82h

Reset

DPL [7:0]

00h

DPL[7:0]: Data pointer Low

Mnemonic: DPH

Address: 83h

Reset

DPH [7:0]

00h

DPH [7:0]: Data pointer High

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