Rainbow Electronics W78C438C - Manual (Page 5)

W78C438C
Publication Release Date: July 1998
- 5 - Revision A1
P8.0
−P8.7 I/O Port
Functions are the same as those of Port 1 in the W78C31, except that they are mapped by the P8
register and not bit-addressable. The P8 register is not a standard register in the W78C32. Its address
is at 0A6H.
INT2 , INT3 External Interrupt, Input
Functions are similar to those of external INT0 , INT1 in the W78C32, except that the functions/status
of these interrupts are determined/shown by the bits in the XICON (External Interrupt Control)
register. The XICON register is bit-addressable but is not a standard register in the W78C32. Its
address is at 0C0H. For details, see the Functional Description below.
EA External Address, Input
Functions same as W78C32.
RST, XTAL1, XTAL2, PSEN , ALE
Functions same as W78C32.
BLOCK DIAGRAM
SFR
RAM
256
Bytes
CPU
Serial
Port
Data Bus
CORE
Interrupt
INT0
Timer0
Timer2
Port 0
Port 1
Port 2
Alternate
Port 8
DP4
AP5
AP6
AP7
Alternate
INT1
Timer1
INT2
INT3
Port 3
Alternate