W741E260 Datasheet, PDF (9/94 Pages) Winbond – 4-BIT FLASH MICROCONTROLLER

W741E260
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
PAGE
Note: R/W means read/write available.
2
R/W
1
R/W
0
R/W
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. Otherwise CF can be stored or be read out by executing MOVA R, CF
or MOV CF, R.
Publication Release Date: March 1998
-9-
Revision A2