C511 datasheet(18/128 Pages) SIEMENS

18 / 128 page

Fundamental Structure

Semiconductor Group

2-3

Special Function Register PSW (Address D0H)

Reset Value : 00H

B Register

The B register is used during multiply and divide and serves as both source and destination. For

other instructions it can be treated as another scratch pad register.

Stack Pointer

The stack pointer (SP) register is 8 bits wide. It is incremented before data is stored during PUSH

and CALL executions and decremented after data is popped during a POP and RET (RETI)

execution, i.e. it always points to the last valid stack byte. While the stack may reside anywhere in

the on-chip RAM, the stack pointer is initialized to 07H after a reset. This causes the stack to begin

a location = 08H above register bank zero. The SP can be read or written under software control.

Bit

Function

Carry Flag

Auxiliary Carry Flag (for BCD operations)

General Purpose Flag

RS1 RS0

Bank 0 selected, data address 00H-07H

Bank 1 selected, data address 08H-0FH

Bank 2 selected, data address 10H-17H

Bank 3 selected, data address 18H-1FH

Overflow Flag

General Purpose Flag

Parity Flag

Set/cleared by hardware each instruction cycle to indicate an odd/even number of

"one" bits in the accumulator, i.e. even parity.

RS1

D0H

PSW

Bit No.

MSB

LSB

RS0

C511 Datasheet(PDF) 18 Page - Siemens Semiconductor Group