5

M67204H

4141J–AERO–04/07

Expansion Out/Half-full

Flag (XO/HF)

This is a dual-purpose output. In the single device mode, when Expansion In (XI) is con-

nected to ground, this output acts as an indication of a half-full memory.

After half the memory is filled and on the falling edge of the next write operation, the

Half-Full Flag (HF) will be set to low and will remain set until the difference between the

write and read pointers is less than or equal to half of the total memory of the device.

The Half-Full Flag (HF) is then reset by the rising edge of the read operation.

In the Depth Expansion Mode, Expansion In (XI) is connected to Expansion Out (XO) of

the previous device. This output acts as a signal to the next device in the Daisy Chain by

providing a pulse to the next device when the previous device reaches the last memory

location.

DATA output for 9-bit wide data. This data is in a high impedance condition whenever

Read (R) is in a high state.