Rainbow Electronics AT29C257 - Manual (Page 8)

Software Protected Program Cycle Waveform
(1, 2, 3)
Notes: 1. A6 through A14 must specify the page address
during each high to low transition of WE (or CE)
after the software code has been entered.
2. OE must be high when WE and CE are both low.
3. All bytes that are not loaded within the page being
programmed will be indeterminate.
LOAD DATA
TO
PAGE (64 BYTES)
(4)
LOAD DATA A0
TO
ADDRESS 5555
LOAD DATA 55
TO
ADDRESS 2AAA
LOAD DATA AA
TO
ADDRESS 5555
Notes for software program code:
1. Data Format: I/O7 - I/O0 (Hex);
Address Format: A14 - A0 (Hex).
2. Data Protect state will be activated at end of program cycle.
3. Data Protect state will be deactivated at end of program
period.
4. 64-bytes of data must be loaded.
ENTER DATA
PROTECT STATE
(2)
WRITES ENABLED
Software Data
Protection Enable
Algorithm
(1)
LOAD DATA
TO
PAGE (64 BYTES)
(4)
LOAD DATA 55
TO
ADDRESS 2AAA
LOAD DATA AA
TO
ADDRESS 5555
LOAD DATA 80
TO
ADDRESS 5555
LOAD DATA 55
TO
ADDRESS 2AAA
LOAD DATA AA
TO
ADDRESS 5555
LOAD DATA 20
TO
ADDRESS 5555
EXIT DATA
PROTECT STATE
(3)
Software Data
Protection Disable
Algorithm
(1)
4-112
AT29C257