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2

Truth Table

H

= HIGH Voltage Level

L

= LOW Voltage Level

X

= Immaterial

 = LOW-to-HIGH Transition

Note 1: The data output functions may be enabled or disabled by various signals at the OE and DIR inputs. Data input functions are always enabled;

i.e., data at the bus pins will be stored on every LOW-to-HIGH transition of the appropriate clock inputs.

Real Time Transfer

A-Bus to B-Bus

FIGURE 1.

Real Time Transfer

B-Bus to A-Bus

FIGURE 2.

Storage from

Bus to Register

FIGURE 3.

Transfer from

Register to Bus

FIGURE 4.

Inputs

Data I/O

(Note 1)

Function

OE

DIR

CPAB

CPBA

SAB

SBA

H

X

H or L

H or L

X

X

Isolation

H

X



X

X

X

Input

Input

H

X

X



X

X

L

H

X

X

L

X

L

H



X

L

X

Input

L

H

H or L

X

H

X

L

H



X

H

X

L

L

X

X

X

L

L

L

X



X

L

Output

Input

L

L

X

H or L

X

H

L

L

X



X

H