W78E54B

- 10 -

OPERATIONS

P3.0

(A9

CTRL)

P3.1

(A13

CTRL)

P3.2

(A14

CTRL)

P3.3

(OE

CTRL)

P3.6

( CE )

P3.7

( OE )

EA

P2, P1

(A15..A0)

P0

(D7..D0)

NOTE

Read

0

0

0

0

0

0

1

Address

Data Out

Output Disable

0

0

0

0

0

1

1

X

Hi-Z

Program

0

0

0

0

0

1

Address

Data In

Program Verify

0

0

0

0

1

0

Address

Data Out

@3

Erase

1

0

0

0

0

1

A0:0,

others: X

Data In

0FFH

@4

Erase Verify

1

0

0

0

1

0

Address

Data Out

@5

Program/Erase

Inhibit

X

0

0

0

1

1

X

X

Notes:

3. The program verify operation follows behind the program operation.

4. This erase operation will erase all the on-chip Flash EPROM cells and the Security bits.

5. The erase verify operation follows behind the erase operation.

SECURITY BITS

During the on-chip Flash EPROM operation mode, the Flash EPROM can be programmed and verified

repeatedly. Until the code inside the Flash EPROM is confirmed OK, the code can be protected. The

protection of Flash EPROM and those operations on it are described below.

The W78E54B has a Security Register which can not be accessed in normal mode. These registers

can only be accessed from the Flash EPROM operation mode. Those bits of the Security Register can

not be changed once they have been programmed from high to low. They can only be reset through

erase-all operation. The Security Register is addressed in the Flash EPROM operation mode by

address #0FFFFh.