We can Copy Protected Microchip Processor PIC18F4620 Eeprom, please view the Microchip Processor PIC18F4620 features for your reference:

TBLPTR is used in reads, writes and erases of the Flash program memory. When a TBLRD is executed, all 22 bits of the TBLPTR determine which byte is read from program memory into TABLAT. When a TBLWT is executed, the three LSbs of the Table Pointer register (TBLPTR<2:0>) determine which of the
8 program memory holding registers is written to.

When the timed write to program memory begins (via the WR bit), the 19 MSbs of the TBLPTR (TBLPTR<21:3>) determine which program memory block of 8 bytes is written to. For more detail, see Section 6.5 “Writing to Flash Program Memory”. When an erase of program memory is executed, the 16 MSbs of the Table Pointer register (TBLPTR<21:6>) point to the 64-byte block that will be erased when Copy Protected Microchip Processor PIC18F4620 Eeprom.

The Least Significant bits (TBLPTR<5:0>) are ignored. Figure 6-3 describes the relevant boundaries of
TBLPTR based on Flash program memory operations. The TBLRD instruction is used to retrieve data from program memory and places it into data RAM. Table reads from program memory are performed one byte at a time.

TBLPTR points to a byte address in program space. Executing TBLRD places the byte pointed to into
TABLAT. In addition, TBLPTR can be modified automatically for the next table read operation. The internal program memory is typically organized by words. The Least Significant bit of the address selects between the high and low bytes of the word. Figure 6-4 shows the interface between the internal program memory and the TABLAT if Copy Protected Microchip Processor PIC18F4620 Eeprom.

The minimum erase block is 32 words or 64 bytes. Only through the use of an external programmer, or through ICSP control, can larger blocks of program memory be bulk erased. Word erase in the Flash array is not supported after COPY MICROCONTROLLER.