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8 Bit Computer Programs

These programs run on the 8 bit computer as well as my simulator.

Please note, I will need to clean up the assembly code once I write an assembler.

• Addition from the videos
  • This is one of Ben's example programs. It add two numbers stored in memory.
  • Comments:
    • The numbers are stored at addresses 14 and 15.
  • Pseudo Assembly

    Load 15
    Add 14
    Output
    Halt
    

  • Machine Code:

    0x1f 0x2e 0xe0 0xf0 0 0 0 0 0 0 0 0 0 0 12 30
    

  • Note, the simulator will take either hex or decimal, so the data is stored as decimal.
  • Expected output: 42 for the data provided.
• Addition and Subtraction, from the videos
  • This is one of Ben's example programs.
  • It add two numbers stored in memory, then it subtracts a third.
  • Comments:
    • The numbers are stored at addresses 13, 14 and 15.
  • Pseudo Assembly

    Load 15
    Add 14
    Sub 13
    Output
    Halt
    

  • Machine Code:

    0x1f 0x2e 0x3d  0xe0 0xf0 0 0 0 0 0 0 0 10 12 30
    

  • Expected output: 32 for the data provided.
• Infinite Loop, count up, from the videos
  • This is one of Ben's example programs.
  • This prints out multiples of three.
  • Comments:
    • The numbers are stored at address 15.
    • This was a test of the jump instruction.
    • This is an infinite loop.
  • Pseudo Assembly

    LoadI 3
    Store 15
    LoadI 0
    Add 15
    out
    Jump 3
    

  • Machine Code:

    0x53 0x4f 0x50 0x2f 0xe0 0x63
    

  • Expected output: Many values, increasing by 3.

Infinite Loop count up and down, from the videos

• This is one of Ben's example programs.
• It counts up by an amount until overflow, then down by the same amount until 0
• Comments:
  • The numbers are stored at address 15.
  • This is an infinite loop.
  • This is a test of the conditional jumps.
• Pseudo Assembly

  out
  add 15
  jumpC 4
  jump 0
  sub 15
  out
  jumpz 0
  jump 4
  
  15: 1
  

• Machine Code:

  0xe0 0x2f 0x74 0x60 0x3f 0xe0 0x80 0x64 0 0 0 0 0 0 0 1
  

• Expected output: Many values, counting up, then down, then up, then down, .

Multiply two numbers, from the videos

• This is one of Ben's example programs.
• This will multiply two numbers and store the results.
• Comments:
  • The numbers are stored at address 13(x*y), 14(x), and 15(y).
  • The constant 1 is stored at 12
  • This is an infinite loop.
• Pseudo Assembly

  load 14
  subtract 12
  jumpc 6
  load 13
  output
  halt
  store 14
  load 13
  add 15
  store 13
  jump 0
  
  12: 1
  13: 0
  14: 12 
  15: 5
  

• Machine Code:

  0x1e 0x3c 0x76 0x1d 0xe0 0xf0 0x4e 0x1d 0x2f 0x4d 0x60 0 1 0 12 5 
  

• The multiples of x up to x*y, x = 12, y = 5 in this case.

Fibonacci Sequence, From The Shamblog

• This is a modified version of Ben's example programs.
• This will compute the Fibonacci sequence.
• Comments:

  x = 1
  y = 0
  while no overflow
     x = x + y
     tmp = x + y // just to cause overflow before next computation
           

• Pseudo Assembly

  loadI 1
  store 14
  loadI  0
  store 15
  out
  load 14
  add 15
  store 14
  out
  load 15
  add 14
  jumpc 13
  jump 3
  halt
  

• Machine Code:

  0x51 0x4e 0x50 0x4f 0xe0 0x1e 0x2f 0x4e 0xe0 0x1f 0x2e 0x7d 0x63 0xf0