Contents: Introduction to Assembly, Instruction Cycle, Addressing Modes | Chapter 3 Assembly language programming Introduction to Assembly High level vs. Assembly High level languages • More programmer friendly. • More ISA independent. • Each high-level statement translates to several instructions in the ISA of the computer. Assembly language • Lower level, closer to ISA. • Very ISA-dependent. • Each instruction specifies a single ISA instruction. • Makes low level programming more user friendly. • More efficient code. Microcomputer principles and applications Introduction to Assembly Assembler syntax {label[:]} mnemonic {operand list} {;comment} • Symbols: ⋄ ⋄ ⋄ • Used as labels, constants, and substitution values and stored in a symbol table. A symbol name is a string of up to 200 alphanumeric characters (A-Z, a-z, 0-9, $, and _), cannot contain embedded blanks, is case sensitive. The first character cannot be a number. Labels: ⋄ Labels are symbols. Microcomputer principles and applications Introduction to Assembly Assembler syntax {label[:]} mnemonic {operand list} {;comment} • Labels: ⋄ ⋄ ⋄ ⋄ • Begined in column 1 and is optionally followed by a colon. The value of a label is the current value of the Location Counter (address within program). A label on a line by itself is a valid statement. Labels used locally within a file must be unique. Mnemonics: ⋄ Cannot start in column 1. If it does, it is interpreted as a label. Microcomputer principles and applications Introduction to Assembly Assembler syntax {label[:]} mnemonic {operand list} {;comment} • Mnemonics: ⋄ ⋄ ⋄ • Contains one of the following items: Instruction, Assembler directive, Macro directive, Macro invocation. A label on a line by itself is a valid statement. Labels used locally within a file must be unique. Operands: ⋄ ⋄ ⋄ Contains one or more operands. An operand may consist of: symbols, constants, expressions. Operands are separated with commas. Microcomputer principles and .
