4FN8105.1
February 12, 2007
Page Write Operation
The page write feature of the X28C010/X28HT010 allows
the entire memory to be written in 5 seconds. Page write
allows two to two hundred fifty-six bytes of data to be
consecutively written to the X28C010/X28HT010 prior to the
commencement of the internal programming cycle. The host
can fetch data from another device within the system during
a page write operation (change the source address), but the
page ad d ress (A8 through A16) for each subsequent valid
write cycle to the part during this operation must be the same
as the initial page address.
The page write mode can be initiated during any write
operation. Following the initial byte write cycle, the host can
write an additional one to two hundre d fifty six bytes in the
same manner as the first byte was written. Each successive
byte load cycle, started by the WE HIGH to LOW transition,
must begin within 100µs of the falling edge of the preceding
WE. If a subsequent WE HIGH to LOW transition is not
detected within 100µs, the internal automatic programming
cycle will commence. There is no page write window
limitation. Effectively the page write window is infinitely wide,
so long as the host continues to access the device within the
byte load cycle time of 100µs.
Write Operation Status Bits
The X28C010/X28HT010 provides the user two write
operation status bits. These can be used to optimize a
system write cycle time. The status bits are mapped onto the
I/O bus as shown in Figure 1.
DATA Polling (I/O7)
The X28C010/X28HT010 features DATA Polling as a
method to indicate to the host system that the byte write or
page write cycle has completed. DATA Polling allows a
simple bit test operation to determine the status of the
X28C010/X28HT010, eliminati ng additional interrupt inputs
or external hardware. During the internal programming cycle,
any attempt to read the last byte written will produce the
complement of that data on I/O7 (i.e., write data = 0xx x xxxx,
read data = 1xxx xxxx). Once the programming cycle is
complete, I/O7 will reflect true data. Note: If the
X28C010/X28HT010 is in the prot ected state, and an illegal
write operation is attempted, DATA Polling will not operate.
Toggle Bit (I/O6)
The X28C010/X28HT010 also provides anothe r method for
determining when the internal write cycle is complete. During
the internal programming cycle, I/O6 will toggle from HIGH to
LOW and LOW to HIGH on subsequent attempts to read the
device. When the internal cycle is complete the toggling will
cease and the device will be accessible for additional read or
write operations.
DATA Polling I/O7
5TBDP 43210I/O
Reserved
Toggle Bit
DATA Polling
FIGURE 1. STATUS BIT ASSIGNMENT
CE
OE
WE
I/O7
X28C010
Last
Write
HIGH Z
VOL
VIH
A0-A14 AnAnAnAnAnAn
VOH
An
Ready
FIGURE 2. DATA POLLING BUS SEQUENCE
X28C010, X28HT010