X28C512/X28C513
DATA Polling I/O
7
Figure 2a. DATA Polling Bus Sequence
LAST
WRITE
WE
CE
OE
V
IH
V
HIGH Z
OH
I/O
7
V
OL
X28C512/513
READY
A –A
0
15
An
An
An
An
An
An
An
3856 FHD F07.1
Figure 2b. DATA Polling Software Flow
DATA Polling can effectively halve the time for writing to
the X28C512/513. The timing diagram in Figure 2a
illustrates the sequence of events on the bus. The
softwareflowdiagraminFigure2billustratesonemethod
of implementing the routine.
WRITE DATA
NO
WRITES
COMPLETE?
YES
SAVE LAST DATA
AND ADDRESS
READ LAST
ADDRESS
IO
NO
7
COMPARE?
YES
X28C512
READY
3856 FHD F08
4