CAT28C010
Advanced Information
DATA Polling
Toggle Bit
DATA polling is provided to indicate the completion of
write cycle. Once a byte write or page write cycle is
initiated, attempting to read the last byte written will
output the complement of that data on I/O7 (I/O0–I/O6
are indeterminate) until the programming cycle is com-
plete. Upon completion of the self-timed write cycle, all
I/O’s will output true data during a read cycle.
InadditiontotheDATAPollingfeatureoftheCAT28C010,
the device offers an additional method for determining
the completion of a write cycle. While a write cycle is in
progress, reading data from the device will result in I/O6
togglingbetweenoneandzero. However, oncethewrite
is complete, I/O6 stops toggling and valid data can be
read from the device.
Figure 7. DATA Polling
ADDRESS
CE
WE
t
OEH
t
OES
t
OE
OE
t
WC
= X
I/O
D
IN
= X
D
D
OUT
= X
7
OUT
28C010 F10
Figure 8. Toggle Bit
WE
CE
OE
t
OEH
t
OES
t
OE
(1)
(1)
I/O
6
t
WC
28C010 F11
Note:
(1) Beginning and ending state of I/O is indeterminate.
6
Doc. No. 25093-00 7/99 P-1
8