STC12LE5616AD datasheet(69/377 Pages) STC

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Accumulator

ACC is the Accumulator register. The mnemonics for accumulator-specific instructions, however, refer to the

accumulator simply as A.

B-Register

The B register is used during multiply and divide operations. For other instructions it can be treated as another

scratch pad register.

Stack Pointer

The Stack Pointer register is 8 bits wide. It is incrementde before data is stored during PUSH and CALL

executions. While the stack may reside anywhee in on-chip RAM, the Stack Pointer is initialized to 07H after a

reset.

Therefore, the first value pushed on the stack is placed at location 0x08, which is also the first

initialized to a location in the data memory not being used for data storage. The stack depth can extend

up to 256 bytes.

Some common SFRs of standard 8051 are shown as below.

Program Status Word(PSW)

The program status word(PSW) contains several status bits that reflect the current state of the CPU. The PSW,

shown below, resides in the SFR space. It contains the Carry bit, the Auxiliary Carry(for BCD operation), the two

The Carry bit, other than serving the function of a Carry bit in arithmetic operations, also serves as the

“Accumulator” for a number of Boolean operations.

The bits RS0 and RS1 are used to select one of the four register banks shown in the previous page. A number of

instructions refer to these RAM locations as R0 through R7.

The Parity bit reflects the number of 1s in the Accumulator. P=1 if the Accumulator contains an odd number of 1s

and otherwise P=0.

Data Pointer Register (DPTR)

The Data Pointer (DPTR) consists of a high byte (DPH) and a low byte (DPL). Its intended function is to hold a

16-bit address. It may be manipulated as a 16-bit register or as two independent 8-bit registers.

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