By completing this set of 12 mini challenges you will write programs using Little Man Computer using all the instructions of the LMC instruction set (See below). You will start with basic Input / Process / Output challenges based on sequencing. You will then investigate branching instructions (BRP, BRZ, BRA) to write programs using selection (a.k.a. branching) and iteration (a.k.a. loops).
LMC Instruction Set
Note that in the following table “xx” refers to a memory address (aka mailbox) in the RAM. The online LMC simulator has 100 different mailboxes in the RAM ranging from 00 to 99.
|INP||INPUT||Retrieve user input and stores it in the accumulator.||901|
|OUT||OUTPUT||Output the value stored in the accumulator.||902|
|LDA||LOAD||Load the Accumulator with the contents of the memory address given.||5xx|
|STA||STORE||Store the value in the Accumulator in the memory address given.||3xx|
|ADD||ADD||Add the contents of the memory address to the Accumulator||1xx|
|SUB||SUBTRACT||Subtract the contents of the memory address from the Accumulator||2xx|
|BRP||BRANCH IF POSITIVE||Branch/Jump to the address given if the Accumulator is zero or positive.||8xx|
|BRZ||BRANCH IF ZERO||Branch/Jump to the address given if the Accumulator is zero.||7xx|
|BRA||BRANCH ALWAYS||Branch/Jump to the address given.||6xx|
|HLT||HALT||Stop the code||000|
|DAT||DATA LOCATION||Used to associate a label to a free memory address. An optional value can also be used to be stored at the memory address.|