Week 1 COM221 Operating Systems
Week 1 COM221 Operating Systems. 2 Chapter 2 Objectives Identify chips, adapter cards, and other components of a motherboard Describe the components of.
Jan 04, 2016
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Week 1
COM221 Operating Systems
2
Chapter 2 Objectives
Identify chips, adapter cards, and other components of a motherboard
Identify chips, adapter cards, and other components of a motherboard
Describe the components of a processor and how they complete a machine cycle
Describe the components of a processor and how they complete a machine cycle
Identify characteristics of various personal computer processors on the market today
Identify characteristics of various personal computer processors on the market today
Define a bit and describe how a series of bits represents data
Define a bit and describe how a series of bits represents data
Explain how programs transfer inand out of memory
Explain how programs transfer inand out of memory
Differentiate among the varioustypes of memory
Differentiate among the varioustypes of memory
Describe the types of expansion slots and adapter cards
Describe the types of expansion slots and adapter cards
Explain the differences among a serial port, a parallel port, a USB port, a FireWire port, and other ports
Explain the differences among a serial port, a parallel port, a USB port, a FireWire port, and other ports
Describe how buses contribute to acomputer’s processing speed
Describe how buses contribute to acomputer’s processing speed
Identify components in mobile computersand mobile devices
Identify components in mobile computersand mobile devices
Understand how to clean a system unitUnderstand how to clean a system unit
Understand the different innovations in operating systems development; Appreciate the basic role of an
operating system; Identify the major operating system software subsystem managers and their functions;
Differentiate among the types of machine hardware on which operating systems run and the basic
functionality of the three memory allocation schemes presented.
Understand the different innovations in operating systems development; Appreciate the basic role of an
operating system; Identify the major operating system software subsystem managers and their functions;
Differentiate among the types of machine hardware on which operating systems run and the basic
functionality of the three memory allocation schemes presented.
3
What is an Operating System?
A computer consists of Software (Programs) and Hardware (CPU, Memory, Motherboard etc). The operating system is a software component of a computer system that manages all the hardware and software. It controls every file, every device, allocation of processing time and memory. It controls who can use the system and how.
4
Operating System Software
Every operating system performs four essential functions. Memory management, processor management, Device management and file management. Each function is carried out with the respective manager Memory manager, Processor Manager, Device manager and File manager. Each of the processor must perform the following tasks
Monitor its resources continuously Apply policies on how each resource is allocated and to whom Allocate the resources that is handling Deallocate the resources when needed
5
Kernel
Kernel is the core of the operating system. It resides in main memory at all times and performs the most essential tasks such as managing memory, process scheduling etc
6
Data Representation
How do computers represent data?
Recognize only two discrete states: on or off
Use a binary system to recognize two states
Use Number system with two unique digits: 0 and 1, called bits (short for binary digits)
Most computers are digital
7
Data Representation
What is a byte? Eight bits grouped together as a unit Provides enough different combinations of 0s and 1s
to represent 256 individual characters Numbers Uppercase
and lowercase letters
Punctuation marks
Other
8
Data Representation
How is a letter converted to binary form and back?
Step 3.The system unit converts the scan code for the capital letter T to its ASCII binary code (01010100) and stores it in memory for processing.
Step 2.An electronic signal for the capital letter T is sent to the system unit.
Step 4.After processing, the binary code for the capital letter T is converted to an image, and displayed on the output device.
T
Step 1.The user presses the capital letter T (SHIFT+T key) on the keyboard.
9
Memory
What is memory? Electronic components that
store instructions, data, and results
Consists of one or more chips on motherboard orother circuit board
Each byte stored in unique location called an address, similar to seats in a concert hall
10
Memory
How is memory measured?
Term Abbreviation Approximate Size
Kilobyte KB or K 1 thousand bytes
Megabyte MB 1 million bytes
Gigabyte GB 1 billion bytes
Terabyte TB 1 trillion bytes
By number of bytes available for storage
11
Memory
ROM (Read Only Memory)- Special memory used to store programs(ex. BIOS) that boot
the computer and perform diagnostics
- Non-volatile
- Variations: PROM, EPROM, EEPROM, Flash Memory
12
Storage(Disk)
Hard disk- A magnetic disk on which you can store large volumes data.
- Internal hard disk & portable hard disk
- Several platters with tracks, read/write head and an access arm
- 100Gbyte – Tbyte
- Term : IDE, ATA – disk drive implementation that integrates the controller on the disk drive itself
Other disks – Zip, Jaz, tapes, CD, DVD
13
Characteristics of Memory
The term location refers to whether memory is internal and external to the computer. Internal memory is often equated with main memory. There are other forms of internal memory.
The processor requires its own local memory, in the form of registers.
The control unit portion of the processor may also require its own internal memory.
Cash is another form of internal memory.
External memory consists of peripheral storage devices, such as disk and tape, that are accessible to the processor via I/O controllers.
14
Characteristics of Memory
Capacity is an obvious characteristic of internal memory, this is typically expressed in terms of bytes (1 byte = 8 bits) or words. Common word lengths are 8, 16, and 32 bits. External memory capacity is typically expressed in terms of
bytes.
15
Three concepts for internal memory: Word:
The «natural» unit of organization of memory. The size of the word is typically equal to the number of bits used to represent a number and to the instruction length.
Addressable units: The addressable unit is the word. Many systems allow addressing at the byte level. The relationship between the length in bits A of an address and the
number N of addressable units is 2A=N. Unit of transfer:
For main memory, this is the number of bits read out of or written into memory at a time. The unit of transfer need not equal a word or an addressable unit.
For external memory, data are often transferred in much larger units than a word, and these are refered to as blocks.
16
The two most important characteristics of memory
From a user’s point of view the two most important characteristics of memory are capacity and performance.
Three performance parametres are used: Access time (latency):
For random-access memory, this is the time it takes to perform a read or write operation, that is, the time from the instant that an address is presented to the memory to the instant that data have been stored or made available for use.
For non-random-access-memory, access time is the time it takes to position the read-write mechanism at the desired location.
17
The two most important characteristics of memory
From a user’s point of view the two most important characteristics of memory are capacity and performance.
Three performance parametres are used: Memory cycle time:
This concept is primarily applied to random-access memory and consists of the access time plus any additional time required before a second access can commence.
18
Memory
What is random access memory (RAM)?
The more RAM a The more RAM a computer has, the computer has, the faster it respondsfaster it responds
Also called Also called main memory main memory
or primary or primary storagestorage
Most RAM is Most RAM is volatile, it is lost volatile, it is lost when computer’s when computer’s
power is power is turned offturned off
Memory chips that can be Memory chips that can be read from and written read from and written
to by processorto by processor
19
Memory
How do program instructions transfer in and out of RAM?Step 1. When you start the computer, certain operating system files are loaded into RAM from the hard disk. The operating system displays the user interface on the screen.
Operating system Operating system instructionsinstructions
Web browser Web browser instructionsinstructions
Paint program Paint program instructionsinstructions
Operating system Operating system interfaceinterface
Web browser Web browser windowwindow
Paint program Paint program windowwindow
Web browser Web browser program instructions program instructions
are removed from are removed from RAMRAM
Web browser Web browser window is no window is no
longer displayed on longer displayed on desktopdesktop
Step 2. When you start a Web browser, the program’s instructions are loaded into RAM from the hard disk. The Web browser window is displayed on the screen.
Step 3. When you start a paint program, the program’s instructions are loaded into RAM from the hard disk. The paint program, along with the Web Browser and certain operating system instructions are in RAM. The paint program window is displayed on the screen.
Step 4. When you quit a program, such as the Web browser, its program instructions are removed from RAM. The Web browser is no longer displayed on the screen.
RAM
RAM
20
Must be Must be re-energized re-energized
constantlyconstantly
Do not have toDo not have tobe re-energizedbe re-energized
as often asas often asDRAMDRAM
Most Most common common
typetype
Faster and Faster and more reliable more reliable than DRAM than DRAM
chipschips
Memory
What are two basic types of RAM chips?
Static Static RAM RAM
(SRAM)(SRAM)Dynamic Dynamic RAM RAM (DRAM)(DRAM)
Newer Type: Magnetoresistive RAM (MRAM)
21
Memory. Organization
The basic element of a semiconductor memory is the memory cell. Although a variety of electronic technologies are used, all semiconductor memory cells share certain properties: They exhibit two stable (or semistable) states, which can be
used to represent binary 1 and 0. They are capable of being written into (at least once), to set
the state. They are capable of being read to sense the state.
22
DRAM and SRAM
One distinguishing characteristic of RAM is that it is possible both to read data from the memory and to write new data into the memory easily and rapidly. Both the reading and writing are accomplished through the use of electrical signals.
The other distinguishing characteristic of RAM is that it is volatile. A RAM must be provided with a constant power supply. If the power is interrupted, then the data are lost.
Thus, RAM can be used only as temporary storage. The two traditional forms of RAM used in computer
are DRAM and SRAM.
23
Dynamic RAM
RAM technology is divided into two technologies: dynamic and static. A dynamic RAM (DRAM) is made with cells that store data
as charge on capacitors (or condenser is a passive electronic component).
The presence or absence of charge on a capacitor is interpreted as a binary 1 or 0, because capacitors have a natural tendency to discharge, dynamic RAMs require periodic charge refreshing to maintain data storage. The term dynamic refers to this tendency of the stored charge to leak away, even with power continuously applied.
24
Semiconductor Memory TypesMemory Type Category Erasure Write Mechanism Volatility Usage Price
Random-access memory (RAM)
Electrically, byte level
Electrically
Read-only memory (ROM)
Not possible Masks
Programmable ROM (PROM)
Electrically
Erasable PROM (EPROM)
UV light, chip level
Electrically
Electrically Erasable PROM (EEPROM)
Electrically, byte level
Electrically
Flash memory Electrically, block level
Electrically
25
Static RAM
In contrast, a static RAM (SRAM) is a digital device, using the same logic elements used in the processor. A static RAM will hold its data as long as power is supplied
to it.
26
SRAM versus DRAM
Both static and dynamic RAMs are volatile: that is, power must be continuously supplied to the memory to preserve the bit values. A dynamic memory cell is simpler and smaller than a static memory
cell. Thus, a DRAM is more dense (smaller cells = more cells per unit area) and less expensive than a corresponding SRAM. On the other hand, a DRAM requires the supporting refresh circuitry (circuits). For larger memories, the fixed cost of the refresh circuitry is more than compensated for by the smaller variable cost of DRAM cells. Thus, DRAMs tend to be favored for large memory requirements.
A final point is that SRAMs are generally somewhat faster than DRAMs. Because of these relative characteristics, SRAM is used for cache memory (both on and off chip), and DRAM is used for main memory.
27
Memory
Where does memory reside? Resides on small circuit
board called memory module
Memory slots on motherboard hold memory modules
28
Memory
How much RAM does an application require? Depends on the types of
software you plan to use
For optimal performance, you need more than minimum specifications
29
Memory
How much RAM do you need? Depends on type of applications you intend to run
on your computerRAM
Use
512 MB to 1 GB 1 GB to 2 GB 2 GB and up
• Home and business
users managing
personal finances• Using standard
application software
such as word processing• Using educational
or entertainment
CD-ROMs• Communicating with
others on the Web
• Users requiring more advanced
multimedia capabilities• Running number-intensive
accounting, financial, or
spreadsheet programs• Using voice recognition• Working with videos, music, and
digital imaging• Creating Web sites• Participating in video conferences• Playing Internet games
• Power users creating
professional Web sites• Running sophisticated
CAD, 3D design, or
other graphics-intensive
software
30
Memory
What is cache?
L1 cache built into processor L2 cache slower but has larger capacity L2 advanced transfer cache is faster,
built directly on processor chip L3 cache is separate from processor
chip on motherboard (L3 is only on computers that use L2 advanced transfer cache)
Helps speed computer processes by storing frequently used instructions and data
Also called memory cache
31
Cache memory principles
Cache memory is intended to give memory speed approaching that of the fastest memories available, and at the same time provide a large memory size at the price of less expensive types of semiconductor memories.
The concept is illustrated in the figure below. There is a relatively large and slow main memory together with a smaller, faster cache memory.
The cache contains a copy of portions of main memory.
32
Cache memory principles
When the processor attempts to read a word of memory, a check is made to determine if the word is in the cache. If so, the word is delivered to the process. If not, a block of main memory, consisting of some fixed number of words, is read into the cache and then the word is delivered to the processor.
CPU Cache Main memory
Word transfer
Block transfer
33
Computer Components
Virtually all contemporary computer designs are based on concepts developed by John von Neumann at the Institute for Advanced Studies, Princeton.
Such a design is referred to as the von Neumann architecture and is based on three key concepts:
- Data and instructions are stored in a single read-write memory.
- The contents of this memory are addressable by location, without regard to the type of data contained there.
- Execution occurs in a sequential fashion (unless explicitly modified) from one instruction to the next.
34
The Components of the System Unit: Differentiate among various styles of system units; Computer Function
The basic function performed by a computer is execution of a program, which consists of a set of instructions stored in memory.
The processor does the actual work by executing instructions specified in the program.
This section provides an overview of the key elements of program execution.
Instruction processing consists of two steps: The processor reads (fetches) instructions from memory
one at a time and executes each instruction.
35
Computer Function
Program execution consists of repeating the process of instruction fetch and instruction execution.- The instruction execution may involve several operations
and depends on the nature of the instruction.
36
The von Neumann Machine
The computer consists of the following:
- A main memory, which stores both data and instructions- An arithmetic and logic unit (ALU) capable of operating on binary data- A control unit, which interprets the instructions in memory and causes them
to be executed- Input and output (I/O) equipment operated by the control unit
37
The von Neumann Machine
With rare exceptions, all of today’s computers have the same general structure and function and are thus referred to as von Neumann machines.
Description of the operation of the computer- The memory of the computer consists of 1000 storage locations,
called words, of 40 binary digits (bits) each. Both data and instructions are stored there. Numbers must be represented in binary form, and each instruction also has to be a binary code.
38
The von Neumann Machine 0 1 39
Sign bit
Figure 1.3 Memory Formats.
0 3928208
Right instructionLeft instruction
AddressOpcode AddressOpcode
(a) Number word
(b) Instruction word
39
The von Neumann Machine The memory of the computer consists of 1000 storage locations, called words, of 40
binary digits (bits) each. Both data and instructions are stored there. Numbers must be represented in binary form, and each instruction also has to be a binary code.
Figure 1.3 illustrates these formats. Each number is represented by a sign bit and a 39-bit value. A word may also contain two 20 bit instructions, with each instruction consisting of an 8-bit operation code (opcode specifying the operation to be performed and a 12-bit address designating one of the words in memory (numbered from 0 to 999).- Physical memory that is internal to the computer- Random Access Memory , Read & Write- An array of boxes, each of which can hold a single byte of information- CPU can manipulate only data that is in main memory- Amount of main memory determines how many programs can be executed at a time. - Type: DRAM(Dynamic Ram) – need to be refreshed, SRAM(Static Ram)- no need to refresh, faster, expensive- Volatile – lose its data when power is out- Swapping : A technique that maintains portion of data in the memory when the memory is not large enough- Virtual memory
The System Unit
What is the system unit? Case that contains
electronic components of the computer used to process data Sometimes called
the chassis
The System Unit
What are common components inside the system unit?
Memory Adapter cards
Sound card Video card
Drive bays Power supply
Processor
The System Unit
What is the motherboard? Main circuit board
of the system unit Contains
expansion slots, processor chips, and memory slots
Also called system board
The System Unit
What is a chip? Small piece of semi-conducting material on which
integrated circuits are etched Integrated circuits contain many microscopic pathways
capable of carrying electrical current Chips are packaged so they can be attached to a
circuit board
44
Memory Management
Main-Memory is a large array of words or bytes. Each word or byte has its own address. Main memory is a repository of quickly accessible data shared by the CPU and I/O devices. The central processor reads instructions from main memory during the instruction-fetch cycle, and both reads and writes data from main memory during the data-fetch cycle. The I/O operations implemented via DMA also read and write data in main memory. The main memory is generally the only large storage device that the CPU is able to address and access directly.
45
Memory Management
To improve both the utilization of CPU and the speed of the computer's response to its users, we must keep several programs in memory. There are many different memory-management schemes. The major activities of an operating system in regard to memory-management are:
Keep track of which part of memory are currently being used and by whom
Decide which processes are loaded into memory when memory space becomes available.
Allocate and deallocate memory space as needed.
ProcessorProcessor
Control Control UnitUnit
Arithmetic Arithmetic Logic Unit (ALU)Logic Unit (ALU)
Arithmetic Arithmetic Logic Unit (ALU)Logic Unit (ALU)
Processor
What is the central processing unit (CPU)?
InputInputDevicesDevices
StorageStorageDevicesDevices
OutputOutputDevicesDevices
Interprets and carries out basic instructions that operate a computer
MemoryMemoryDataData InformationInformation
InstructionsInstructionsDataData
InformatioInformationn
InstructionsInstructionsDataData
InformatioInformationn
Control Control UnitUnit
Control unit directs and coordinates operations in computer
Arithmetic logic unit (ALU) performs arithmetic, comparison, and logical operations
Also called the processor
Processor
What is pipelining? Processor begins fetching second instruction before
completing machine cycle for first instruction Results in faster processing
Stores location Stores location from where instruction from where instruction
was fetchedwas fetched
Processor
Stores Stores instruction while it is instruction while it is
being decodedbeing decoded
What is a register?
Stores data Stores data while ALU while ALU computes itcomputes it
Stores results Stores results of calculationof calculation
Temporary high-speed storage area that holds data and instructions
Processor
What are dual-core and multi-core processors? A dual-core processor is a single chip that contains two
separate processors A multi-core processor is a chip with two or more
separate processors Each processor on a dual-core/multi-core chip generally
runs at a slower clock speed, but increase overall performance
Processor
What are the guidelines for selecting a processor?
Processor
What are heat sinks, heat pipes, and liquid cooling?
Heat sink—component with fins that cools processor
Heat pipee—smaller device for notebook computers
Liquid cooling—uses a continuous flow of fluids to transfer heat away
Processor
What is parallel processing?Control ProcessorControl Processor
Processor 1Processor 1
MemoryMemory
Processor 2Processor 2
MemoryMemory
Processor 3Processor 3
MemoryMemory
Processor 4Processor 4
MemoryMemory
Results combined
Using multiple processors simultaneously to execute a program faster
Requires special software to divide problem and bring results together
Structure and Function
A computer is a complex system; contemporary computers contain millions of elementary electronic components.
A hierarchical system is a set of interrelated subsystems. The system consists of a set of components and their
interrelationships. The behavior at each level depends only on a simplified, abstracted characterization of the system at the next lower level. At each level, the designer is concerned with structure and function: 1. Function: The operation of each individual component as part of the structure.2. Structure: The way in which the components are interrelated.
1.1 Function
Both the structure and functioning of a computer are, in essence, simple. Figure 1.1 depicts the basic function that a computer can perform. In general terms, there are only four: Data Processing Data storage Data movement Control
DataMovementapparatus
DataProcessing
facility
DataStoragefacility
Controlmechanism
Figure 1.1 A Functional View of the Computer
1.2 Function
The computer must be able to process data. The data may take a wide variety of forms, and the range of processing requirements is broad.
It is also essential that a computer stores data.
- The computer performs a short-term data storage
- The computer performs a long-term data storage
- Files of data are stored on the computer for subsequent retrieval and update.
1.3 Function
The computer must be able to move data between itself and the outside world.
- The computer’s operating environment consists of devices that serve as either sources or destination of data.
- When data are received from or delivered to a device that is directly connected to the computer, the process is known as input-output (I/O), and the device is referred to as a peripheral.
- When data are moved over longer distances, to or from a remote device, the process is known as data communications.
1.4 Function
There must be control of these three functions.
- Within the computer, a control unit manages the computer’s resources and orchestrates the performance of its functional parts in response to those instructions.
2.1 Structure
There are four main structural components- Central processing unit (CPU): Controls the operation of the
computer and performs its data processing functions; often simply referred to as processor
- Main memory: Stores data
- I/O: Moves data between the computer and its external environment
- System interconnection: Some mechanism that provides for communication among CPU, main memory, and I/O
- Traditionally, there has been just a single CPU. In recent years, there has been increasing use of multiple processors in a single computer.
2.2 Structure
The most interesting and complex component is the CPU; its major structural components are as follows:- Control Unit: Controls the operation of the CPU and the
computer
- Arithmetic and logic unit (ALU): Performs the computer’s data processing functions
- Registers: Provides storage internal to the CPU
- CPU interconnection: Some mechanism that provides for communication among the control unit, ALU, and registers
2.3 Structure
Systeminterconnection
Centralprocessing
unit
Input/output
Mainmemory
COMPUTER
COMPUTER
Figure 1.2 The Computer: Top-Level Structure
I/O Interfacing (Peripheral devices) I/O
Any program, operation or device that transfers data to or from a computer and to or from a peripheral device
Peripheral Device A computer device, such as a CD-ROM drive or printer, that is not part of the essential
computer, i.e., the memory and microprocessor. External & Internal
Bus A collection of wires through which data is transmitted from one part of a computer to
another Internal Bus(System Bus, Host bus) between internal computer component to CPU & main
memory Expansion Bus for expansion board(card) to CPU & main memory Performance : Bus size (with) (bit), Bus clock speed (MHz) Type : ISA(old), PCI, AGP, SCSI
(Bus) Controller A device( a chip) that controls the transfer of data from a computer to a peripheral device and
vice versa
I/O Interfacing (Peripheral devices)
63
User Command interface
Every operating system provides an interface that accepts commands from the operator. This interface can be in the form of a command-line interface or in the form of a Graphical User Interface (GUI). Command line interfaces were very common on early systems and UNIX systems. GUI (Windows) interfaces are widespread used on Apple and Windows operating systems.
64
Types of operating systems
Operating systems can be distinguished into five categories based on their response time and how the data is entered in to the system. Batch Systems :
In a batch system programs to be run were collected in a designated area, read onto a magnetic tape using a small, relatively inexpensive computer. After collecting jobs in this manner for a prescribed period of time, the tape was rewound and mounted on a tape drive connected to the main computer where the programs were run one after the other. The output from each program was collected onto a second tape. When the entire batch was processed, the operator removed both tapes and passed the one with the outputs on to be printed by the same small computer connected to a printer. The operator then mounted another tape with another batch of programs to be run.
65
Types of operating systems
Interactive Systems Interactive systems are a variation of multiprogramming systems
because they allow several users to be on-line at the same time. The computer can provide fast interactive service to several users, and programmers can debug their programs in a shorter period of time than was possible with batch systems. This is because not all users are issuing commands to the computer at the same time. For example, of 300 users logged on there may be only 20 percent actively working at any given time allowing the CPU to handle their requests in a timely manner. In addition, some of the commands may take a small amount of CPU time to complete, for example to compile a student program, while others may take a longer time to finish, thus balancing the workload.
66
Types of operating systems
Real Time Systems Real-time systems are used in time critical environments
such as vehicle control or patient monitoring where failures in the system could lead to loss of life or major destruction of property. They are usually considered dedicated systems which spend most of the time on a single job. Work such as laboratory experiment monitoring, or environment control within buildings requires continuous processing, with little opportunity to use the computer for unrelated purposes.
67
Types of operating systems
Hybrid Systems Hybrid Systems are a combination of batch and Interactive
systems. Batch jobs are running the background when the interactive activity is low. They are utilizing system resources efficiently.
68
Types of operating systems
Embedded Systems Embedded systems are computers systems that are placed
inside other devices. They have all the main components of a computer system (CPU, memory) but are performing specific functions to enhance the functionality of the device. They can only run specific programs and they make very efficient use of their limited resources.
69
Desktop and server Operating systems
Operating systems can be classified based on the users’ accessibility into Desktop operating systems and Server operating Systems.
70
Desktop Operating systems
Desktop Operating systems are used on single user systems. They are used on personal computers that perform general tasks such as writing documents and internet browsing. Examples of Desktop operating systems are Windows XP, Windows 7, Linux Ubuntu desktop edition.
71
Server Operating systems
Server operating systems are used on multiuser systems. Many users can access the system concurrently via the network. They perform functions such as File sharing, mail servers, web servers, application servers. Examples of server operating systems are Windows Server 2008, UNIX and IBM Mainframes.
72
Device management
The Device Manager is in charge of monitoring the device connected to the Computer systems such as disk drives, printers, ports etc. It allocates and deallocates these resources to the running process based on scheduling policy.
73
History of Operating Systems
Historically operating systems have been tightly related to the computer architecture, it is good idea to study the history of operating systems from the architecture of the computers on which they run. Operating systems have evolved through a number of distinct phases or generations which corresponds roughly to the decades.
74
History of Operating SystemsThe 1940's - First Generations
The first generation of Computers were bulky and expensive. They were used only by research institutions and universities. Each one was unique. They had no operating systems. Machines of the time were so primitive that programs were often entered one bit at time on rows of mechanical switches (plug boards). Programming languages were unknown (not even assembly languages). The machines were operated by the programmers and it was mainly manual work. They were poorly utilized. The programs were only understandable form the person that develops them.
75
History of Operating SystemsThe 1950's - Second Generation
Second generation computers were started to be used by business. They were still very expensive and only big business could afford them. The General Motors Research Laboratories implemented the first operating systems in early 1950's for their IBM 701. The system of the 50's generally ran one job at a time. These were called single-stream batch processing systems because programs and data were submitted in groups or batches.
76
History of Operating SystemsThe 1960's - Third Generation
The systems of the 1960's were also batch processing systems, but they were able to take better advantage of the computer's resources by running several jobs at once. So operating systems designers developed the concept of multiprogramming in which several jobs are in main memory at once; a processor is switched from job to job as needed to keep several jobs advancing while keeping the peripheral devices in use.
77
History of Operating SystemsThe 1970’s
CPUs were becoming faster but the I/O devices were still slow. Multiprogramming was limited by the memory capacity of the system. Memory was very expensive. The concept of virtual memory was developed where not the whole program needed to be loaded in the memory. Part of it could be kept in secondary storage and loaded only when needed. Organization of data into databases was becoming popular. Database tools were becoming available.
78
History of Operating SystemsThe 1980’s
Computers became much more cost effective. Many functions were carried out by separated hardware components with build-in system software. Programmers did not have to deal directly with the hardware and their job was simpler. Multiprocessing (more than one processor) was introduced where a single job is served by many processors. It was the era of the evolution of personal computers that were able to connect with each. Network operating systems were introduced that allow networked computers to share resources.
79
History of Operating SystemsThe 1990’s
Internet was evolved connecting computers worldwide. Computer’s networking capability was enhanced. Web accessibility and email became standard on almost all operating systems. New devices appeared that can connect to computers to provide multimedia capabilities such as microphones, speakers, DVD drives, CD drives, projectors etc.
80
History of Operating SystemsThe 2000’s
Processing speed of computers was significantly improved with the introduction of multicore processors. A single CPU chip can hold multiple processors cores that act as separate processors and therefore multiplying their processing capacity.
Virtualization started to become popular. Virtualization allows us to run multiple operating systems on a single server and share resources.
Related Documents
