W741C204 Просмотр технического описания (PDF) - Winbond

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W741C204

4-BIT MICROCONTROLLER

Winbond 

Preliminary W741C20X

The first sixteen addresses (00H to 0FH) in the data memory are known as the working registers

(WR). The other data memory is used as general memory and cannot operate directly with immediate

data. The relationship between data memory locations and the page register (PAGE) in indirect

addressing mode is described in the next section.

2. Page Register (PAGE)

The page register is organized as a 4-bit binary register. The bit descriptions are as follows:

3

2

1

0

PAGE

R/W R/W R/W

Note: R/W means read/write available.

Bit 3 is reserved.

Bit 2, Bit 1, Bit 0 Indirect addressing mode preselect bits:

000 = Page 0 (00H - 0FH)

001 = Page 1 (10H - 1FH)

010 = Page 2 (20H - 2FH)

011 = Page 3 (30H - 3FH)

100 = Page 4 (40H - 4FH)

101 = Page 5 (50H - 5FH)

110 = Page 6 (60H - 6FH)

111 = Page 7 (70H - 7FH)

Accumulator (ACC)

The accumulator (ACC) is a 4-bit register used to hold results from the ALU and transfer data

between the memory, I/O ports, and registers.

Arithmetic and Logic Unit (ALU)

This is a circuit which performs arithmetic and logic operations. The ALU provides the following

functions:

• Logic operations: ANL, XRL, ORL

• Branch decisions: JB0, JB1, JB2, JB3, JNZ, JZ, JC, JNC, DSKZ, DSKNZ, SKB0, SKB1, SKB2,

SKB3

• Shift operations: SHRC, RRC, SHLC, RLC

• Binary additions/subtractions: ADC, SBC, ADD, SUB, ADU, DEC, INC

After any of the above instructions are executed, the status of the carry flag (CF) and zero flag (ZF) is

stored in the internal registers. CF can be read out by executing MOVA R, CF.

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