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FIGURE 4. A Vertical Expansion Scheme

Horizontal Expansion—The 74F433 can be horizontally

expanded, without external logic, to store long words (in

multiples of 4-bits). The interconnections necessary to form

a 64-word by 12-bit FIFO are shown in Figure 5. Using the

same technique, any FIFO of 64-words by 4n-bits can be

constructed, where n is the number of devices.

The right-most (most significant) device is connected to the

TTS inputs of all devices. Similarly, the ORE output of the

most significant device is connected to the TOS inputs of

all devices. As in the vertical expansion scheme, horizontal

expansion does not sacrifice any of the 74F433 flexibility

for serial/parallel input and output.

It should be noted that the horizontal expansion scheme

shown in Figure 5 exacts a penalty in speed.

Horizontal and Vertical Expansion—The 74F433 can be

expanded in both the horizontal and vertical directions

without any external components and without sacrificing

any of its FIFO flexibility for serial/parallel input and output.

The interconnections necessary to form a 127-word by 16-

bit FIFO are shown in Figure 6. Using the same technique,

any FIFO of (63m

+1)-words by 4n-bits can be configured,

where m is the number of devices in a column and n is the

number of devices in a row. Figure 7 and Figure 8 illustrate

the timing diagrams for serial data entry and extraction for

the FIFO shown in Figure 6. Figure 9 illustrates the final