Configuring Ports 1, 2, 5, And 6 (Bidirectional Ports); Ports 1, 2, 5, And 6 Internal Structure (87C196La, Lb Only) - Intel 87C196CA Supplement To User’s Manual

Internal Bus
P x _REG
SFDATA
P x _DRV
SFDIR
P x _MODE
Read Port
RESET#
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-
0
1
0
1
Sample
Latch
P x _PIN
Q D
LE
PH1 Clock
300ns Delay
RESET#
Any Write to P x _MODE
V
RESET#
V
150 to 200
Buffer
Medium
Pullup
Q3
V
SS
Weak
R Pullup
Q
Q4
S
V
SS
I/O PORTS
CC
Q1
I/O Pin
Q2
SS
R1
A5265-01
5-3