P87C591 pdf datasheet (Microco

EPROM Programming
1. Connect VDD = 5V, VPP = 5V, Connect a a crystal to pins XTAL1 and XTAL2 or a clock to XTAL1 pin.
2. Connect the mode select inputs as specified at Table 3 for programming code and PROG=1.
3. Wait 10μSec and change VPP = 5V to VPP = 12.75V
4. Apply Address and data of the programmed byte, wait 24 clock cycles (minimum).
5. Generate five active low pulses on pin PROG to program the byte.
6. Apply Address and data of the next programmed byte, wait 24 clock cycles (minimum).
7. Generate five active low pulses on pin PROG to program the byte.
8. repeat 6,7 for all the programmed bytes.
9. Wait 10μSec and change VPP = 12.75V to VPP = 5V
Encryption Table Programming
The 87C591 has a 64 byte encryption table.
1. Connect VDD = 5V, VPP = 5V, Connect a crystal to pins XTAL1 and XTAL2 or a clock to XTAL1 pin.
2. Connect the mode select inputs as specified at Table 3 for Encryption Table programming and PROG=1.
3. Wait 10μSec and change VPP = 5V to VPP = 12.75V
4. Apply Address and data of the programmed byte, wait 24 clock cycles (minimum).
5. Generate five active low pulses on pin PROG to program the byte.
6. Apply Address and data of the next programmed byte, wait 24 clock cycles (minimum).
7. Generate five active low pulses on pin PROG to program the byte.
8. repeat 6,7 for all the Encryption Table bytes.
9. Wait 10μSec and change VPP from 12.75V to 5V