W79E201 Datasheet, PDF (26/87 Pages) Winbond – 8-BIT MICROCONTROLLER

W79E201
BIT NAME
FUNCTION
7
CY
Carry flag: Set for an arithmetic operation which results in a carry being generated
from the ALU. It is also used as the accumulator for the bit operations.
6
AC
Auxiliary carry: Set when the previous operation resulted in a carry from the high
order nibble.
5
F0 User flag 0: The General purpose flag that can be set or cleared by the user.
4 RS1 Register bank select bits:
3 RS0 Register bank select bits:
2
OV
Overflow flag: Set when a carry was generated from the seventh bit but not from
the 8th bit as a result of the previous operation, or vice-versa.
1
F1
User Flag 1: The General purpose flag that can be set or cleared by the user by
software.
0
P
Parity flag: Set/cleared by hardware to indicate odd/even number of 1's in the
accumulator.
RS.1-0: Register bank select bits:
RS1
RS0
0
0
0
1
1
0
1
1
Watchdog Control
Bit:
7
-
6
POR
Mnemonic: WDCON
REGISTER BANK
0
1
2
3
ADDRESS
00-07h
08-0Fh
10-17h
18-1Fh
5
4
3
2
1
0
-
-
WDIF WTRF EWT RWT
Address: D8h
BIT NAME
FUNCTION
7
-
Reserved.
Power-on reset flag. Hardware will set this flag on a power up condition. This flag
6 POR can be read or written by software. A write by software is the only way to clear
this bit once it is set.
5
-
Reserved.
4
-
Reserved.
Watchdog Timer Interrupt Flag. If the watchdog interrupt is enabled, hardware will
3
WDIF
set this bit to indicate that the watchdog interrupt has occurred. If the interrupt is
not enabled, then this bit indicates that the time-out period has elapsed. This bit
must be cleared by software.
Watchdog Timer Reset Flag. Hardware will set this bit when the watchdog timer
2
WTRF
causes a reset. Software can read it but must clear it manually. A power-fail reset
will also clear the bit. This bit helps software in determining the cause of a reset. If
EWT = 0, the watchdog timer will have no affect on this bit.
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