LMC

• What is the mnemonic for loading to the accumulator in LMC?

  LDA
• What is the numerical/machine code for loading to the accumulator?

  5
• What does the LOAD instruction do in LMC?

  Loads mailbox contents to the accumulator
• What is the mnemonic for storing from the accumulator?

  STA
• What is the numerical/machine code for storing from the accumulator?

  3
• What does the STORE instruction do in LMC?

  Stores accumulator contents to a mailbox
• What is the mnemonic for the ADD instruction?

  ADD
• What is the numerical/machine code for the ADD instruction?

  1
• What does the ADD instruction do in LMC?

  Adds mailbox contents to the accumulator
• What happens if the ADD instruction results in a sum larger than 3 digits?

  The actions of the accumulator are undefined
• What is the mnemonic for the SUBTRACT instruction?

  SUB
• What is the numerical/machine code for the SUBTRACT instruction?

  2
• What does the SUBTRACT instruction do in LMC?

  Subtracts mailbox contents from the accumulator
• What happens if the SUBTRACT instruction results in a negative result?

  A negative flag will be set
• What is the mnemonic for the INPUT instruction?


  INP
• What is the numerical/machine code for the INPUT instruction?

  901
• What does the INPUT instruction do in LMC?

  Copies value from "in box" to accumulator
• What is the mnemonic for the OUTPUT instruction?

  OUT
• What is the numerical/machine code for the OUTPUT instruction?

  902
• What does the OUTPUT instruction do in LMC?

  Copies accumulator value to "out box"
• What is the mnemonic for the END program instruction?

  HLT
• What is the numerical/machine code for the END program instruction?

  000
• What does the HLT instruction do in LMC?

  Stops executing the program
• What is the mnemonic for the BRANCH IF ZERO instruction?

  BRZ
• What is the numerical/machine code for the BRANCH IF ZERO instruction?

  7
• What does the BRZ instruction do in LMC?

  Branches if accumulator is zero
• What is the mnemonic for the BRANCH IF ZERO OR POSITIVE instruction?

  BRP
• What is the numerical/machine code for the BRANCH IF ZERO OR POSITIVE instruction?

  8
• What does the BRP instruction do in LMC?

  Branches if accumulator is zero or positive
• What is the mnemonic for the BRANCH ALWAYS instruction?

  BRA
• What is the numerical/machine code for the BRANCH ALWAYS instruction?

  6
• What does the BRA instruction do in LMC?

  Branches to the given address
• What is the mnemonic for the DATA LOCATION instruction?

  DAT
• What does the DAT instruction do in LMC?

  Reserves the next mailbox for data storage
• What is the summary of LMC instructions and their codes?

  • Load: LDA, 5xx
  • Store: STA, 3xx
  • Add: ADD, 1xx
  • Subtract: SUB, 2xx
  • Input: INP, 901
  • Output: OUT, 902
  • End: HLT, 000
  • Branch if zero: BRZ, 7xx
  • Branch if zero or positive: BRP, 8xx
  • Branch always: BRA, 6xx
  • Data storage: DAT