Microprocessor PIC18F46K20 Flash Program Replication needs to crack mcu pic18f46k20 fuse bit by focus ion beam and extract code from embedded IC chip memory;
The Table Pointer (TBLPTR) register addresses a byte within the program memory. The TBLPTR is comprised of three SFR registers: Table Pointer Upper Byte, Table Pointer High Byte and Table Pointer Low Byte (TBLPTRU:TBLPTRH:TBLPTRL).
These three registers join to form a 22-bit wide pointer. The low-order 21 bits allow the device to address up to 2 Mbytes of program memory space. The 22nd bit allows access to the device ID, the user ID and the Configuration bits will be required also in the process of pic18f24k20 program and data recovery.
The Table Pointer register, TBLPTR, is used by the TBLRD and TBLWT instructions. These instructions can update the TBLPTR in one of four ways based on the table operation. These operations are shown in Table 6-2. These operations on the TBLPTR affect only the low-order 21 bits.
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 directly into the TABLAT register. When a TBLWT is executed the byte in the TABLAT register is written, not to Flash memory but, to a holding register in preparation for a program memory write.
The holding registers constitute a write block which varies depending on the device.The 3, 4, or 5 LSbs of the TBLPTRL register determine which specific address within the holding register block is written to. The MSBs of the Table Pointer have no effect during TBLWT operations.