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2

Logic Symbols

IEEE/IEC

Truth Table

H

HIGH Voltage Level

L

LOW Voltage Level

X

Immaterial

 LOW-to-HIGH Transition

Functional Description

The AC/ACT299 contains eight edge-triggered D-type flip-

flops and the interstage logic necessary to perform syn-

chronous shift left, shift right, parallel load and hold opera-

shown in the Truth Table. All flip-flop outputs are brought

out through 3-STATE buffers to separate I/O pins that also

are also brought out on other pins for expansion in serial

shifting of longer words.

A LOW signal on MR overrides the Select and CP inputs

and resets the flip-flops. All other state changes are initi-

ated by the rising edge of the clock. Inputs can change

when the clock is in either state provided only that the rec-

ommended setup and hold times, relative to the rising edge

of CP, are observed.

buffers and puts the I/O pins in the high impedance state.

In this condition the shift, hold, load and reset operations

can still occur. The 3-STATE buffers are also disabled by

lel load operation.

Inputs

Response

MR

L

X

X

X

HH

H

HL

H

HH

L

H

L

L

X

Hold