
X28VC256
4
DATA
POLLING I/O
7
Figure 2.
DATA
Polling Bus Sequence
3869 FHD F12
Figure 3.
DATA
Polling Software Flow
DATA
Polling can effectively halve the time for writing to
the X28VC256. The timing diagram in Figure 2 illus-
trates the sequence of events on the bus. The software
flow diagram in Figure 3 illustrates one method of
implementing the routine.
3869 FHD F13
WRITE DATA
SAVE LAST DATA
AND ADDRESS
READ LAST
ADDRESS
IO7
COMPARE
X28VC256
READY
NO
YES
WRITES
COMPLETE
NO
YES
CE
OE
WE
I/O7
X28VC256
READY
LAST
WRITE
HIGH Z
VOL
VIH
An
An
An
An
An
An
VOH
An