Question

Please make sure to read the instructions carefully! Must use P8!

• (A) Write the following assembly language program.
  • Start at 6 and counts down by 2 to 0. (No Loops!)
  • Comment each line except STOP and .END.
  • Add something to the output that makes this program uniquely yours.
  • Cut and paste the Assembler Listing into your document.

• (B) Paste a screenshot of the Output area of the Pep8.

• (C) Explain the status bits NZVC at the point STOP is loaded.

Assembler Listing

Screen Shot of Output Area

Explain the status bits NZVC

Answer 1

Greetings!!

A) Code:

BR main ;jump to main

prompt: .ascii "Enter a number: \x00" ;prompt message

out: .ascii "Output:\n" ;output message

nl: .ascii "\n" ;newline character

n: .word 2 ;declaring variable n

main: stro prompt,d ;display prompt message

deci n,d ;read number from the user

stro out,d ;display output message

deco n,d ;display the number as it is

stro nl,d ;newline

lda n,d ;load number to accumulator

suba 2,i ;subtract 2 from accumulator

sta n,d ;save to memory

deco n,d ;display number

stro nl,d ;newline

suba 2,i ;subtract 2

sta n,d ;save to memory

deco n,d ;display number

stro nl,d ;newline

suba 2,i ;subtract 2

sta n,d ;save to memory

deco n,d ;display number

stop

.end

Assembly listing:

-------------------------------------------------------------------------------

Object

Addr code Symbol Mnemon Operand Comment

-------------------------------------------------------------------------------

0000 04001F BR main

0003 456E74 prompt: .ASCII "Enter a number: \x00"

657220

61206E

756D62

65723A

2000

0014 4F7574 out: .ASCII "Output:\n"

707574

3A0A

001C 0A nl: .ASCII "\n"

001D 0002 n: .WORD 2

001F 410003 main: STRO prompt,d

0022 31001D DECI n,d

0025 410014 STRO out,d

0028 39001D DECO n,d

002B 41001C STRO nl,d

002E C1001D LDA n,d

0031 800002 SUBA 2,i

0034 E1001D STA n,d

0037 39001D DECO n,d

003A 41001C STRO nl,d

003D 800002 SUBA 2,i

0040 E1001D STA n,d

0043 39001D DECO n,d

0046 41001C STRO nl,d

0049 800002 SUBA 2,i

004C E1001D STA n,d

004F 39001D DECO n,d

0052 00 STOP

0053 .END

-------------------------------------------------------------------------------

Symbol table

--------------------------------------

Symbol Value Symbol Value

--------------------------------------

main 001F n 001D

nl 001C out 0014

prompt 0003

--------------------------------------

B) Output:

C) Flags:

Hope this helps