SN74ALS234

64 × 4 ASYNCHRONOUS FIRST IN, FIRST OUT MEMORY

SDAS106B − OCTOBER 1986 − REVISED SEPTEMBER 1993

4

POST OFFICE BOX 655303

POST OFFICE BOX 1443

timing diagram

RST

SI

D3 − D0

SO

Q3 − Q0

IR

OR

W1

Don’t Care

Word 1

Word 2

Invalid†

Word 1‡

Word 2

Word 3

Clear

Shift In

W1

Shift Out

W2

Empty

Full

W2

W1

W2

W63

W64

W1

† The last data word shifted out of the FIFO remains at the output until a new word falls through or a RST pulse clears the FIFO.

‡ While the output data is considered valid only when the OR flag is high, the stored data remains at the outputs. Any additional words written into

the FIFO will stack up behind the first word and will not appear at the output until SO is taken low.