W39F010

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6.3

Boot Block Operation

There are two alternatives to set the boot block. The 16K-byte in the top/bottom location of this device

can be locked as boot block, which can be used to store boot codes. It is located in the last 16K bytes

or first 16K bytes of the memory with the address range from 1C000(hex) to 1FFFF(hex) for top

location or 00000(hex) to 03FFF(hex) for bottom location.

See Command Codes for Boot Block Lockout Enable for the specific code. Once this feature is set the

data for the designated block cannot be erased or programmed (programming lockout), other memory

locations can be changed by the regular programming method.

In order to detect whether the boot block feature is set on the first/last 16K-byte block or not, users

can perform software command sequence: enter the product identification mode (see Command

Codes for Identification/Boot Block Lockout Detection for specific code), and then read from address

0002(hex) for first(bottom) location or 1FFF2(hex) for last(top) location.

If the DQ0/DQ1 of output

data is "1," the 16Kbytes boot block programming lockout feature will be activated; if the DQ0/DQ1 of

output data is "0," the lockout feature will be inactivated and the block can be erased/programmed.

To return to normal operation, perform a three-byte command sequence (or an alternate single-byte

command) to exit the identification mode. For the specific code, see Command Codes for

Identification/Boot Block Lockout Detection.

6.3.1

to prevent unintentional writes.

6.3.2

Write Pulse "Glitch" Protection

Noise pulses of less than 10 nS (typical) on #OE, #CE, or #WE will not initiate a write cycle.

6.3.3

Logical Inhibit

#CE and #WE must be a logical zero while #OE is a logical one.

6.3.4

Power-up Write Inhibit

edge of #WE except 5mS delay (see the power up timing in AC Characteristics). The internal state

machine is automatically reset to the read mode on power-up.

6.4

Command Definitions

Device operations are selected by writing specific address and data sequences into the command

register. Writing incorrect address and data values or writing them in the improper sequence will reset

the device to the read mode. "Command Definitions" defines the valid register command sequences.