Question

You can find the detailed description of the instructions for S12 in the reference manual “S12CPUV2.pdf". This document is available in the lab. 1. Example: The following program (1) clear register A, then (2) add 3 to A ten times. It uses the zero flag and BNE with DECB ; this program adds value 3 to register A ten times ; A=0 COUNT EQU 10 ; use 10 for counter LDAB #COUNT ; load the counter CLRA AGAIN ADDA #3 ; add 03 to A (A=sum) DECB ; decrement counter BNE AGAIN ; repeat until COUNT=0 STAA $200 ; send sum to Location $200 2. Problem: Write a program to (1) clear register A, and (2) add 3 to register A fifteen times and place the result in RAM location $1250. Use a RAM location for holding the counter. 3. Problem: The mnemonic BNE stands for ??? 4. Problem: True or false. BNE BACK makes its decision based on the last instruction affecting the Z flag. 5. Problems: BNE HERE is a ???-byte instruction. 6. Problem: Show the hex number value used by the following directives: (a) ASC_DATA EQU'4

Answer 1

Answer:-2)

COUNT    EQU 15

LDAB #COUNT

CLRA

AGAIN ADDA #3

DECB

BNE AGAIN

STAA $1250

Answer:-3)

BNE stands for Branch if Not Equal

Answer:-4)

Yes it is true. BNE BACK make its decision based on the last instruction affecting the zero flag.

Answer:-5)

BNE HERE is a 1 byte instruction