6.3 Device Functional Modes

FUNCTION

INPUTS

REGISTER OUTPUTS

MR

CP

S0

S1

DS0

DS7

I/On

Q0

Q1

…

Q6

Q7

Reset (Clear)

L

X(1)

X

X

X

X

X

L

L

…

L

L

Shift Right

H

h

I

I

X

X

L

q0

…

q5

q6

H

h

I

h

X

X

H

q0

…

q5

q6

Shift Left

H

I

h

X

I

X

q1

q2

…

q7

L

H

I

h

X

h

X

q1

q2

…

q7

H

Hold (do nothing)

H

I

I

X

X

X

q0

q1

…

q6

q7

Parallel Load

H

h

h

X

X

I

L

L

…

L

L

H

h

h

X

X

h

H

H

…

H

H

Table 6-1. Mode Select

Function table 3-state I/O port operating mode

FUNCTION

INPUTS

INPUTS/OUTPUTS

OE1

OE2

S0

S1

Qn (Register)

I/O0 I/O7

Read

Register

L

L

L

X

L

L

L

L

L

X

H

H

L

L

X

L

L

L

L

L

X

L

H

H

Load

Register

X

X

H

H

Qn = I/On

I/On = Inputs

Disable I/O

H

X

X

X

X

(Z)

X

H

X

X

X

(Z)

(1)

H = Input voltage high level.

CD54AC299, CD74AC299, CD74AC323, CD54ACT299, CD74ACT299

SCHS288A – DECEMBER 1998 – REVISED DECEMBER 2024

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