AT89S8253
8-bit Microcontroller with 12 Kbyte Flash and 2K Bytes EEPROM


Fuse:
Fuse1:  0-SerialPrgEn, 1-SerialPrgDis
Fuse2:  0-x2 ClockEn,  1-x2 ClockDis
Fuse3:  0-UsrRowPrgEn  1-UsrRowPrgDis
Fuse4:  0-External Clock En 1-Crystal Clock En

Program Lock Bits:
        LB3 LB2 LB1
Mode1:   1   1   1    No internal memory lock
Mode2:   1   1   0    further programming of the Flash memory is disabled.
Mode3:   1   0   0    programming and verify disabled
Mode4:   0   0   0    Same as Mode3, but external execution is also disabled.