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DATA PROCESSING BASICS
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Multiprogrammingy CPU and Peripheral Devices comparision
y Our aim is to keep CPU busy for most of the time.
y Concurrent processing of programs
y Memory Layout
OS
Job 1
Job 2
Job 3
Job 4
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Multiprogrammingy Services provided by OS in a multiprogramming
environment:
y Memory Protection
y Concurrency Controly Multiprogramming refers to the ability of a computer
to run more than one program concurrently.
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Multiprocessingy Multiprocessing environment uses two or more CPUs
linked together to optimize data processing.
y Also known as:
y Parallel Systemy Tightly Coupled System
y Services provided by the OS:
y Scheduling and balancing
y I/Oy Processing capabilities of systems
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Multiprocessing
CPU 1 CPU 2 CPU n..
Memory
Multiprocessing Architecture
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Multiprocessing
y What is Symmetric Multiprocessing?y What is Asymmetric Multiprocessing?
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Multitaskingy Also known as Time Sharing System.
y Logical extension of multiprogramming system.
y Multitasking enables a computer to be used by morethan one user for more than one application at thesame time. (Multiple users can access the samesystem).
y Such a system switches the attention of CPU amongusers on a time basis.
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Multitasking
Ready Running
Blocked
New
Jobs
Job allocated to CPU
for Execution
Allocated time slice over
Job must wait for I/O
completionI/O Completed
Process Cycle
or
Process state Diagram
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Computer Languagesy Types of Computer languages:
y Low Level Language
y a low-level programming language is a programminglanguage that provides little or no abstraction from acomputer's instruction set architecture.
y The word "low" refers to the small or nonexistent amount ofabstraction between the language and machine language;because of this, low-level languages are sometimesdescribed as being "close to the hardware."
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Computer Languagesy Assembly Language
y An assembly language is a low-level programming languagefor computers, microprocessors, microcontrollers, and otherintegrated circuits.
y It implements a symbolic representation of the binarymachine codes and other constants needed to program agiven CPU architecture.
y This representation is usually defined by the hardwaremanufacturer, and is based on mnemonics.
y An assembly language is thus specific to a certain physical(or virtual) computer architecture.
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Computer Languagesy High Level Language
y A high-level programming language is a programminglanguage with strong abstraction from the details of thecomputer.
y In comparison to low-level programming languages, it mayuse natural language elements, be easier to use, or be moreportable across platforms.
y The first high-level programming language to be designedfor a computer was Plankalkl, created by Konrad Zuse
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Programming Languagesy Definition:An artificial language used to write
instructions that can be translated into machinelanguage and then executed by a computer.
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Programming Languagesy Types of programming languages:
y Assembled Languages
y Fastest of all the languages.
y
These uses assembly macro commands for equivalentmachine code command.
y Scripted Languages (Batch languages orJob ControlLanguages)
y These require a specific environment to run, and cannot run
without it.y "Scripts" are distinct from the core code of the application,
as they are usually written in a different language and areoften created or at least modified by the end-user.
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Programming Languagesy Interpreted Languages
y an interpreted language is a programming language inwhich programs are 'indirectly' executed ("interpreted") byan interpreter program. Ex. HTML, BASIC
y Compiled Languagesy A compiled language is a programming language whose
implementations are typically compilers (translators whichgenerate machine code from source code), and notinterpreters (step-by-step executors of source code, whereno translation takes place).