EER-018
Introduction to Digital Computers
Lecture 22
Reading: "HC05 Understanding Small Microcontrollers" Pages 17-26, 30-36
6805
Microcontroller - general model fits von Neumann architecture
- program memory
- data memory
- address bus and data bus
- inputs/outputs - microcontroller inputs/outputs tend to be simple
- clock
- cpu
Microcontrollers most often used in embedded systems
Registers in the 6805 cpu
- A - accumulator
- X - index register
- SP - stack pointer
- PC - program counter
- CCR - condition code register
Assembly language programming
- instruction set
- opcode and operands
- mnemonic
- assembler
- machine code
- hex notation
Example instructions
- Assembler directives - org, fdb, equ
- 6805 instructions - lda, ldx, mul, dec, bne