SC73P1601

HANGZHOU SILAN MICROELECTRONICS CO.,LTD

REV:1.4

2009.08.03

Http: www.silan.com.cn

Page 7 of 22

7. LL, LH

LL register, 4 bits, LH register, bit. LL[3:0] is the address pointer of RAM, and is used as the general-purpose

register at the same time.

LH register, 4 bits, used as the general-purpose register.

8. RAM

Data memory consists of 16x4 bits and is used to store temporary data and results after a program is executed.

It can address the entire RAM areas by the pointer LL[3:0]. When reset, the contents of RAM are not defined.

We recommend users to initialize it at the beginning of their software program.

9. ALU

The arithmetic and logic unit plays a leading role in performing various operations of 4-bit binaries. The

operation of ALU will change the carry flag (CF) and the zero flag(ZF).

10. Acc

4-bit accumulator, which is in the ALU. It is mostly used to store data and results.

11. CF

Carry flag.

12. SF

Status flag bit, the value of SF is 1 after reset.

13. PR (PR, PR2)

The port mode register, which specifies the input mode or output mode of the I/O port, is 4-bit write-only. When

the value is 1, the corresponding port is set to output mode. PR=0, it is set to input mode. The execution of the

HOLD instruction won’

t affect the I/O modes of operation. When reset, the initialization value is 0000B, and the

port is in input mode.

P52 mode select

PR2.2

PR2.1

PR2.0

P51 mode select

P50 mode select

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