Final answer:
The assembly programs for MPLAB X IDE involve direct and indirect addressing modes to copy a value to memory locations and performing hexadecimal subtraction. Different addressing modes require different sequences of instructions. Adjustments to the FSR registers are necessary when dealing with higher data memory locations.
Step-by-step explanation:
The question involves writing assembly programs using MPLAB X IDE for a microcontroller, specifically to carry out two tasks: copying a value to memory locations using different addressing modes, and performing subtraction.
Direct Addressing Mode:
To copy the value 0x55 to memory locations 0x40 to 0x45, you would write something like:
MOVLW 0x55 ; Load the literal value 0x55 into WREG
MOVWF 0x40 ; Move the value in WREG to address 0x40
MOVWF 0x41 ; Repeat for each address
MOVWF 0x42
MOVWF 0x43
MOVWF 0x44
MOVWF 0x45
Indirect Addressing Mode:
For indirect addressing, you could use the FSR (File Select Register) to point to the address:
MOVLW 0x55 ; Load the literal value 0x55 into WREG
MOVWF FSR0L ; Move base address 0x40 into FSR0L
loop:
MOVWF INDF0 ; Move value in WREG into the indirect address
INCF FSR0L, F, ; Increment the FSR to point to the next address
CPFSEQ 0x46 ; Compare FSR to the last address + 1, skip if equal
GOTO loop ; If not at the last address, repeat the loop
If the data memory locations changed to 0x340 to 0x345, you would need to set up the FSR registers differently to account for the higher address range. Some microcontrollers might require setting up the FSR's high byte.
Subtraction Example:
To subtract 0x6B from 0x4C:
MOVLW 0x6B ; Load the literal value 0x6B into WREG
SUBWF 0x4C, W ; Subtract WREG from the value at address 0x4C
This will subtract the two hexadecimal numbers and store the result either in WREG or the memory location of the first operand, depending on the microcontroller and the specific SUBWF syntax used.