W742E Datasheet, PDF (19/60 Pages) Winbond – 4 BIT MICROCONTROLLER

W742E/C811
3. Indirect Addressing
Bit 12-0 12 11 10 9 8 7 6 5 4 3 2 1 0
RAM addr BH1 BH0 BL3 BL2 BL1 BL0 DP2 DP1 DP0 (WA3 WA2 WA1 WA0)
(WA0-3) is Working register contents ; DP0-3 is RAM page register(PAGE)
BL0-3 is DBKRL register ; BH0-1 is DBKRH register
Example:
MOV
MOV
MOV
MOV
MOV
DBKRL,BL_value
DBKRH,BH_value
PAGE,#Ip
WRq,#In
WRn,@WRq
; set RAM bank
; set RAM page address,(0-07H)
; set WR pointer address;(0-0FH)
; get the contents of WRq pointing addr to WRn
5.5 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.
5.6 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 is 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 MOV R, CF.
5.7 Main Oscillator
The W742E/C811 provides a crystal oscillation circuit to generate the system clock through external
connections. The 3.58 MHz or 400 KHz crystal must be connected to XIN1 and XOUT1, and a
capacitor must be connected to XIN1 and VSS if an accurate frequency is needed.
Crystal
3.58MHz
XIN1
XOUT1
Figure 5-3 System clock oscillator Configuration
- 19 -
Publication Release Date: December 2000
Revision A1