Some Programs

• There are two numbers stored in memory, write a program that will find the difference of these two numbers. Print the result and store it in memory.
  • The code with labels.

    0  load       A  (5)
    1  subtract   B  (6)
    2  store      C  (7)
    3  output 
    4  halt
    5  A
    6  B
    7  C
           

  • Translate that to machine code

    load 5            0x15
    subtract 6        0x36
    store 7           0x47
    output            0xe0
    halt              0xf0
    20                20 
    10                10 
           

  • The program string : 0x15 0x36 0x47 0xe0 0xf0 20 10
  • Do some experiments and see if you can determine when the carry bit is set.
• A positive integer n is stored at memory location 15. Count from 0 up to n.

 0 TOP:  jz   DONE           89
 1       load 14             1e
 2       out                 e0
 3       add 1               2d
 4       store 14            4e
 5       load 15             1f
 6       sub 1               3d
 7       store 15            4f
 8       j top               60
 9 DONE: load 14             1e 
10       output              e0
11       halt                f0
12   
13   1
14   0
15  10

0x89 0x1e 0xe0 0x2d 0x4e 0x1f 0x3d 0x4f 0x60 0x1e 0xe0 0xf0 0 1 0 10