The part of a machine instruction that tells the computer what to do, such as input, add or branch. The operation code is the verb; the operands are the nouns.
"operation code." YourDictionary, n.d. Web. 16 May 2018. <http://www.yourdictionary.com/operation-code>.
operation code. (n.d.). Retrieved May 16th, 2018, from http://www.yourdictionary.com/operation-code