8XC251SA, SB, SP, SQ USER’S MANUAL
14-4
Table 14-1. Programming and Verifying Modes
Mode RST PSEN# V
PP
PROG# Port
0
Port
2
Address
Port 1 (high)
Port 3 (low)
Notes
Program Mode. On-chip
Code Memory
8K 87C251SA,SP
16K 87C251SB,SQ
High Low 5 V,
12.75 V
5 Pulses 68H data
0000H-1FFFH
0000H-3FFFH
1, 4
Verify Mode. On-chip
Code Memory
8K 87/83C251SA,SP
16K 87/83C251SB,SQ
High Low 5 V High 28H data
0000H-1FFFH
0000H-3FFFH
4
Program Mode. Configu-
ration Bytes (UCONFIG0,
UCONFIG1)
87C251S
x
High Low 5 V,
12.75 V
5 Pulses 69H data FFF8H-FFFFH 1, 4
Verify Mode. Configuration
Bytes (UCONFIG0,
UCONFIG1)
8XC251S
x
High Low 5 V High 29H data FFF8H-FFFFH 4
Program Mode. Lock Bits
87C251S
x
High Low 5 V,
12.75 V
25 Pulses 6BH data 0001H-0003H 1, 2
Verify Mode. Lock bits
87C251S
x
, 83C251S
x
High Low 5 V High 2BH data 0000H 3
Program Mode. Encryption
Array
87C251S
x
High Low 5 V,
12.75 V
25 Pulses 6CH data 0000H-007FH 1
Verify Mode. Signature
Bytes
87C251S
x
, 83C251S
x
High Low 5 V High 29H data 0030H,0031H,
0060H,
0061H
NOTES:
1. To program, raise V
PP
to 12.75 V and pulse the PROG# pin. See Figure 14-2 for waveforms.
2. No data input. Identify the lock bits with the address lines as follows: LB3 - 0003H, LB2 - 0002H,
LB1 - 0001H.
3. The three lock bits are verified in a single operation. The states of the lock bits appear simultaneously
at port 2 as follows: LB3 - P2.3, LB2 - P2.2. LB1 - P2.1. High = programmed.
4. For these modes, the internal address is FF:
xxxx
H.
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