Intel 87C196CA, Supplement To User’S Manual

Page: 47 / 136

5-3
I/O PORTS
Figure 5-1. Ports 1, 2, 5, and 6 Internal Structure (87C196LA, LB Only)
5.2.1 Configuring Ports 1, 2, 5, and 6 (Bidirectional Ports)
Using the port mode register, you can individually configure each pin for port 1, 2, 5, and 6 to
operate either as a general-purpose I/O signal (I/O mode) or as a special-function signal (special-
function mode). In either mode, three configurations are possible: complementary output, high-
Q2
Q1
P x _MODE
P x _DRV
SFDIR
0
1
P x _REG
Sample
Latch
PH1 Clock
Internal Bus
SFDATA
Any Write to P x _MODE
Q
R
Weak
Pullup
RESET#
Q3
Q4
Buffer
Read Port
S
300ns Delay
I/O Pin
RESET#
A5265-01
150
Ω
to 200
Ω
R1
0
1
V
SS
Medium
Pullup
V
SS
V
SS
V
CC
RESET#
P x _PIN
D Q
LE