X68257
Software Data Protection
Software Data Protection (SDP) is employed to protect
the entire array against inadvertent writes. To write to
the X68257, a three-byte command sequence must
precede the byte(s) being written.
All write operations, both the command sequence and
any data write operations must conform to the page write
timing requirements.
Writing with SDP
SYMBOL TABLE
WAVEFORM
INPUTS
Must be
steady
May change
from LOW
to HIGH
May change
from HIGH
to LOW
Don’t Care:
Changes
Allowed
N/A
OUTPUTS
Will be
steady
Will change
from LOW
to HIGH
Will change
from HIGH
to LOW
Changing:
State Not
Known
Center Line
is High
Impedance
WRITE AA
TO 5555
WRITE 55
TO 2AAA
WRITE A0
TO 5555
PERFORM BYTE
OR PAGE WRITE
OPERATIONS
WAIT tWC
EXIT ROUTINE
6539 FHD F09.1
6
XICOR [ XICOR INC. ]
