Provide an explanation and the answer: Write a program loop, using a pointer and

Question

Provide an explanation and the answer:

Write a program loop, using a pointer and a counter, that complement the contents of hexadecimal locations 500 through 5FF.

Hex Symbol Description code AND 0 or 8 AND M to AC ADD 1 or 9 Add M to AC, carry to E LDA 2 or A Load AC from M STA 3 or B Store AC in M BUN 4 or C Branch unconditionally to m Save return address in m and BSA 5 or D branch to m 1 SZ 6 or E Increment M and skip if zero CLA 7800 Clear AC CLE 7400 Clear E CMA 7200 Complement AC CME 7100 Complement E CIR 7080 Circulate right E and AC CIL 7040 Circulate left E and AC INC 7020 increment AC SPA 7010 Skip if AC is positive SNA 7008 Skip if AC is negative SZA 7004 Skip if AC is zero SZE 7002 Skip if E is zero HLT 7001 Halt computer INp nput information and clear F800 flag OUT F400 Output information & clear flag SKI F200 Skip if input flag is on SKO F200 Skip if output flag is on ION F080 Turn interrupt on OF F040 Turn interrupt off

Explanation / Answer

Depending on the IDE/Target Device and environment, the name of variables may change, the below given code gives an idea of how the logic will be implemented. This should help you :)

/****************************code begins here****************************/

org 0000h

mov a,#500h            //a is accumulator and we are loading 500h i.e. the address from...
                                 //...where data will start getting complemented as per question

tag: cjne a,#55fh,next    //keep looping till accumulator content i.e. address...

                                          //...reaches 55f, as per question

here: sjmp here           //If accumulator content i.e. address reaches 55f, keep looping here

next: mov e,[a]           //[a]=content at the address stored in a, and it is being moved...

                                    //...to e register, any other can also be used like r1

CME                            //value of e register complemented

mov [a],e                   //complemented value of e is stored back at the address location...

                                  //...stored in a

INC                            //increment value stored at a register, i.e address

goto tag                    //unconditional jump to tag to check condition again, and thus, loop will continue

The code has been written along with comments and the explaination should be suffice

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