Microprocessors?
Why do we need to learn Microprocessors?
The microprocessor is the core of computer systems.
Nowadays many communication, digital entertainment, portable devices, are controlled by them.
A designer should know what types of components he needs, ways to reduce production costs and increase product reliability.
What is a Microprocessor?
The word comes from the combination micro and processor.
Processor means a device that processes whatever. In this context processor means a device that processes numbers, specifically binary numbers, 0’s and 1’s.
To process means to manipulate. It is a general term that describes all manipulation. Again in this content, it means to perform certain operations on the numbers that depend on the microprocessor’s design.
Concept about Microprocessor:
A microprocessor incorporates most or all of the functions of a central processing unit (CPU) on a single integrated circuit (IC).
Die of an Intel 80486DX2 microprocessor (actual size: 12×6.75 mm) in its packaging
Works of a Microprocessor.
The microprocessor is a programmable device that takes in numbers, performs on them arithmetic or logical operations according to the program stored in memory and then produces other numbers as a result.
Words, Bytes, etc.
The earliest microprocessor (the Intel 8088 and Motorola’s 6800) recognized 8-bit words.
They processed information 8-bits at a time. That’s why they are called “8-bit processors”. They can handle large numbers, but in order to process these numbers, they broke them into 8-bit pieces and processed each group of 8-bits separately.
Later microprocessors (8086 and 68000) were designed with 16-bit words.
A group of 8-bits were referred to as a “half-word” or “byte”.
A group of 4 bits is called a “nibble”.
Also, 32 bit groups were given the name “long word”.
Today, all processors manipulate at least 32 bits at a time and there exists microprocessors that can process 64, 80, 128 bits or more at a time.
Arithmetic and Logic Operations:
Every microprocessor has arithmetic operations such as add and subtract as part of its instruction set.
Most microprocessors will have operations such as multiply and divide.
Some of the newer ones will have complex operations such as square root.
In addition, microprocessors have logic operations as well. Such as AND, OR, XOR, shift left, shift right, etc.
Again, the number and types of operations define the microprocessor’s instruction set and depends on the specific microprocessor.
Program: A program is a sequence of instructions that bring data into the microprocessor, processes it and sends it out.
There are many programming languages (C, C++, FORTRAN, and JAVA…) However, these programming languages can be grouped into three main levels (these days a fourth level is developing).
Programming Languages
Machine language
Machine language is the lowest level programming language. It is a language intended to be understood by the microprocessor (the machine) only. In this language, every instruction is described by binary patterns.
e.g. 11001101 may mean 1 + 2
This is the form in which instructions are stored in memory. This is the only form that the microprocessor understands.
Programming Languages
Assembly language
This language is more understandable by humans. In this language, the binary patterns are assigned mnemonics .
e.g. “Add 1,2” is assigned to the machine language pattern 11001101 mentioned above to refer to the operation 1+2.
Programming Languages
High level languages
These are languages like C, PASCAL and FORTRON. These are more natural for humans to use than assembly or machine languages. They are also more compact (i.e. it takes less statements to write the program).
One high level instruction translates into many assembly or machine language instructions.
e.g. x = y + z may translate into: MOV R1 ,1004 MOV R2 ,1000
ADD R1, R2
MOV R1, 1004
Stored in memory:
When a program is entered into a computer, it is stored in memory. Then as the microprocessor starts to execute the instructions, it brings the instructions from memory one at a time.
Memory is also used to hold the data.
The microprocessor reads (brings in) the data from memory when it needs it and writes (stores) the results into memory when it is done.
Produces: For the user to see the result of the execution of the program, the results must be presented in a human readable form.
The results must be presented on an output device.
This can be the monitor, a paper from the printer, a simple LED or many other forms.
So .. What is Microprocessor?
A microprocessor (abbreviated as µP or uP) is a Silicon Chip that contains an electronic central processing unit (CPU).
In the world µP or CPU used interchangeably, which is made from miniaturized transistors and other circuit elements on a single semiconductor integrated circuit (IC).
The integration of the whole CPU onto a single VLSI Chip therefore greatly reduced the cost of processing capacity.
Architectures of Microprocessors:
8-bit designs
16-bit designs
32-bit designs
64-bit designs
Multi-core designs
RISC (Reduced Instruction Set Computer)
CISC (Complex Instruction Set Computer)
Special-purpose designs: Microcontrollers,
Digital Signal Processors (DSP) and Graphics Processing Units (GPU).
Microcontroller (µC):
Microcontroller is an IC dedicated to perform one task.
Integrates the memory and other features of a microprocessor.
A microcontroller is the integration of
Microprocessor
Memory
ROM types – commonly PROM
RAM – Static ram
Microprocessor System vs Microcontroller System:
uP vs. uC
A uP
only is a single-chip CPU
bus is available
RAM capacity, num of port is selectable
RAM is larger than ROM (usually)
A uC
contains a CPU and RAM,ROM , Peripherals, I/O port in a single IC
internal hardware is fixed
Communicate by port
ROM is larger than RAM (usually)
Small power consumption
Single chip, small board
Implementation is easy
Low cost
Microprocessor vs. Microcontroller
Microprocessor
CPU is stand-alone, RAM, ROM, I/O, timer are separate
designer can decide on the amount of ROM, RAM and I/O ports.
expansive
versatility
general-purpose
Microcontroller
CPU, RAM, ROM, I/O and timer are all on a single chip
fix amount of on-chip ROM, RAM, I/O ports
for applications in which cost, power and space are critical
single-purpose
What's a Chip?
A chip is also called an integrated circuit.
Generally it is a small, thin piece of silicon onto which the transistors making up the microprocessor have been etched.
A chip might be as large as an inch on a side and can contain tens of millions of transistors.
Simpler processors might consist of a few thousand transistors etched onto a chip just a few millimeters square.
