16
AT49LD3200(B)
1940B–FLASH–11/01
Boot Block Lockout command, which is a synchronous five-bus cycle operation, must be
performed (refer to Command Definitions table and Program Cycle Waveforms).
A software method is available to determine if programming or erasing of the boot block
is locked out. Issue Boot Block Lockout Verify command and observe DQ
0
~ DQ
7
. If the
data show 00H/02H, the boot block can be programmed or erased; if the data show
01H/03H, the lockout feature has been enabled and the boot block cannot be pro-
grammed or erased. The Boot Block Lockout Verify Exit command should be used to
return to standard operation (refer to Command Definition table and Boot Block Lockout
Verify Waveforms).
The user can override the boot block lockout by taking the MR
pin to 12 volts after the
boot block is activated. When the MR
pin is brought back to TTL levels, the boot block
lockout feature is again active.
