Chapter 17 Microprocessor Fundamentals William Kleitz Digital Electronics with VHDL, Quartus® II...

Chapter 17

Microprocessor Fundamentals

William KleitzDigital Electronics with VHDL, Quartus® II Version

Copyright ©2006 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458

All rights reserved.

Introduction to System Components and Buses

• Microprocessor– general-purpose device– driven by software– perform a specific task

• Support Circuitry– data input switches– output data





• Microprocessor– Intel 8085– Motorola 6800– Zilog Z80– reads program instructions– executes instructions drives external buses– to make connected devices perform functions





• Microprocessor– buses

• groups of conductors

• routed throughout the system

• tapped into by various devices

• share information





• Address Bus– 16 bits wide– generated by microprocessor– to select a particular location or IC to be active

• Data Bus– sends or receives 8 bits of data to or from the

address– bidirectional





• Control Bus– varying width depending on processor used– carries control signals– identifies operation

• Address Decoder– like 74LS138– ensures that only one IC is active– to avoid bus conflict





• Memory– ROM or EPROM

• initialization instructions

• monitor program

• operating system

– RAM• volatile

• used only for temporary storage





• Input Port– provide data to microprocessor via the data bus– octal buffer with tri-state outputs

• Output Port– talk to the outside world– sends data to output device– octal D flip-flop




Software Control of Microprocessor Systems

• Operational changes made with software

• Accumulator– stores information for the microprocessor

• Assembly Language– software that drives the microprocessor– mnemonics

• abbreviation of the operation to be performed




Internal Architecture of a Microprocessor

• 8085A software compatible with 8080A

• See Figure 17-2– internal architecture– functional block diagram

• See Figure 17-3– pin configuration

• Central Processing Unit (CPU)




Figure 17-2

Figure 17-3





• Internal Data Bus

• General-Purpose Registers– B, C, D, E, H, L

• Arithmetic Logic Unit (ALU)– arithmetic operations– five flag flip-flops

• Instruction Register and Decoder– receive instructions interpret and create signals





• Interrupt Control– external digital signal that interrupts the

software during execution

• Stack Pointer– stores address of the last entry on the stack– stack - data storage area in RAM

• Program Counter– 16-bit address of next software instruction




Instruction Execution Within a Microprocessor

• See Figure 17-4

• Load Accumulator

• Store Accumulator

• See Table 17-2– assembly language and machine code listing




Figure 17-4







Hardware Requirements for Basic I/O Programming

• Memory-Mapped I/O– input and output devices accessed as if they

were memory locations

• I/O-Mapped I/O– identify input and output devices by an 8-bit

port number




Writing Assembly Language and Machine Language Programs

• Assembler– translates mnemonic into hexadecimal machine

code and stores in memory address

• Compiler– High-level languages

• Pascal, FORTRAN, C++, BASIC

– get reduced to machine language before execution




Writing Assembly Language and Machine Language Programs

• Assembly language translates directly to machine code

• See Table 17-3– program in three languages– opcodes







Survey of Microprocessors and Manufacturers

• See Table 17-4







Summary

• A system designer should consider using a microprocessor instead of logic circuitry whenever an application involves making calculations, making decisions based on external stimuli, and maintaining memory of past events.

• A microprocessor is the heart of a computer system. It reads and acts on program instructions given to it by a programmer




Summary

• A microprocessor system has three buses: address, data, control.

• Microprocessors operate on instructions given to them in the form of machine code (1’s and 0’s). The machine code is generated by a higher-level language like C or assembly language.




Summary

• The Intel 8085A is an 8-bit microprocessor. It has 7 internal registers, an 8-bit data bus, an arithmetic/logic unit, and several input/output functions.

• Program instructions are executed inside the microprocessor by the instruction decoder, which issues the machine cycle timing and initiates input/output operations.




Summary

• The microprocessor provides the appropriate logic levels on the data and address buses and takes care of the timing of all control signals output to the connected interface circuitry.

• Assembly language instructions are written using mnemonic abbreviations and then converted into machine language so that they can be interpreted by the microprocessor.




Summary

• Higher-level languages like C or Pascal are easier to write than assembly language, but they are not as memory efficient or as fast. All languages must be converted into a machine language matching that of the microprocessor before they can be executed.




Date post:	23-Dec-2015
Category:	Documents
Upload:	bennett-mathews
View:	227 times
Download:	0 times

Chapter 17 Microprocessor Fundamentals William Kleitz Digital Electronics with VHDL, Quartus® II...

Documents