DDCA Ch6 - Part 18: Decoding Machine Language & Addressing Operands

Introduction to Machine Language Instructions

In this section, the video introduces how to read machine language instructions and discusses the addressing of operands in assembly and machine language.

Understanding Assembly Language Instructions

• The instructions in assembly language have corresponding op codes.

• R-type instructions like add and subtract share an op code of 51 but differ based on funct 3 and funct 7 bits.

Different Types of Instructions

• Add-i is an I-type instruction with an op code of 19.

• Various types of instructions include branches (op code: 99), load word (op code: 7), store word (op code: 35), jump and link (op code: 111), jump and link register (op code: 103), load upper immediate (op code: 55).

Interpreting Machine Language Code

• To interpret machine language, convert hexadecimal numbers to binary, analyze op codes, funct fields, and extract fields based on the instruction type.

Decoding Machine Language Instructions

This section delves into decoding machine language instructions by examining specific examples.

Deciphering Instruction Types

• Analyzing the bits of a machine language instruction reveals its type; for example, identifying whether it's an R-type or I-type instruction.

• Understanding op codes helps identify the instruction format; for instance, recognizing if it's an add-i type instruction based on the op code.

Unpacking Binary Representation

• Converting hexadecimal numbers into binary aids in unpacking fields such as source and destination registers from machine language instructions.

• For instance, determining that a particular instruction is a subtract involves analyzing op codes, func3, func7 bits along with other fields like source and destination registers.