# Microprocessors / debug lab calculation and comparisons

See and follow the attached LAB. Below is just a preview of the attached LAB.

The objective of this lab experiment is to introduce you to assembly language programming for solving mathematical problems. You will use DEBUG to conduct this lab.

The sun is 93,000,000 miles from the Earth. The speed of light is 186,000 miles per second. How long does it take a ray of light to reach the Earth? The correct answer is 8 minutes, 20 seconds.

1.   Open a command window (or DosBox), start DEBUG, and enter these commands:

a
mov dx,1
mov ax,6b48
mov bx,00ba
div bx
mov bl,3c
div bl

r
t 6
q

2.   Remember that a screenshot showing your DEBUG results should be included in your lab report.

3.   What is the final value in the AX register? Does it represent some combination of 8 and 20?
Hint: Remember that DEBUG only works with hexadecimal numbers.

4.   Explain how the calculations were performed in SUN.SCR. For example, were the numbers 93,000,000 and 186,000 represented anywhere? If not, why not?

5.   Open a command window (or DosBox), start DEBUG, and enter the following commands. What is the final value in AL? Explain why this is correct.

a 200
db 5
db 8
db 4
db 7
db 6

a 100
mov si,200
mov al,[si]
mov ah,0
mov bh,0
movbl,[si+1]
movbl,[si+2]
movbl,[si+3]
movbl,[si+4]
mov bl,5
div bl

r
t 0e
q

6.   Open a command window (or DosBox), start DEBUG, and enter the following commands.

a
mov al,20
cmp al,10
cmp al,20

r

t 3
q

7.   Discuss the relationship between the instructions and the results indicated by the flags.
Hint: See Example 4.7 beginning on page 102 in Chapter 4 of your assigned textbook.

8.   Repeat step 4 using these commands:

a
mov al,90
cmp al,80
cmp al,a0

r
t 3
q