Enter new code:

Instructions:

1 Byte instructions

• 0 = Halt
• 1 = Add (R0 = R0 + R1)
• 2 = Subtract (R0 = R0 - R1)
• 3 = Increment R0 (R0 = R0 + 1)
• 4 = Increment R1 (R1 = R1 + 1)
• 5 = Decrement R0 (R0 = R0 - 1)
• 6 = Decrement R1 (R1 = R1 - 1)
• 7 = Ring Bell

2 Byte Instructions

value of the second byte is called <data>

• 8 = Print <data> (The nemerical value of <data> is printed)
• 9 = Load value at address <data> into R0
• 10 = Load value at address <data> into R1
• 11 = Store R0 into address <data>
• 12 = Store R1 into address <data>
• 13 = Jump to address <data>
• 14 = Jump to address <data> if R0 == 0
• 15 = Jump to address <data> if R0 != 0
• 24 = Print ASCII <data>

Start UP

• All registers are set to 0
• All memoty locations are set to 0
• The program is read into memory. The first instruction into address 0, and so on
• the fetch-execute cycle begins

Fetch-Execute Cycle

• The instruction at the address given by IP is loaded into IS
• The IP is increment by 1 (is IS contains a one byte instruction) or by 2 (if IS contains a 2 byte instruction)
• The instruction in IS is executed
• Repeat until IS = HALT
• If the instruction is not in the above table, then the results will be undefinded behavior