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Mode 3: With FIFO Full, Shift-In is Held HIGH

in Anticipation of an Empty Location

Sequence of Operation

1. The FIFO is initially full and Shift-In goes HIGH. OR is

initially HIGH. Shift-Out is LOW. IR is LOW.

2. Shift-Out is pulsed HIGH, Shift-Out pulse propagates

and the first data word is latched on the rising edge of

SO. OR falls on this edge. On the falling edge of SO,

the second data word appears after propagation delay

LOW.

after SO falls, indicating that the FIFO is no longer full.

rising, indicating the FIFO is once more full.

5. Shift-In is brought LOW to complete the shift-in process

and maintain normal operation.

Note: MR and FULL are HIGH; OE is LOW.

FIGURE 3. Modes of Operation Mode 3