Operating systems

Lecture 1

DEFINITIONS

Ştefan Stăncescu

Note: • The following definitions intuitive aim:

achieving an agreement between IT specialists,

• and apply:

only in IT (information technology).

• Subject- conscious existence.

• Object– unconscious existence.

• Sign– object that represents the:• another object, usually more complex • dynamics (time evolution) of the object,• effects of these dynamics in other objects.

The meaning of a sign

is the object it represents.

The semantics (of an existing, of a topic observer)

is the existing value of that topic, namely

the representation that influence the existence,

of the meaning of this existence,

to the subject observer.

The semantics of a sign (for a subject) is the object semantic or

the transformation semantic signified for subject.

Sign retain the important meaningful features (semantic) for a subject interested observer,

in circumstances where original object influences the observer.

Signs are relative to the observer subject

• The model is the complex sign, made of simple signs, corresponding to a

complex object with the samestructure of simple objects.

The model is necessary because it is an effective means of knowledge of nature through virtual experiments,

on the assembly of signs, instead of experimenting on real

objects.

– Semiotics is the science of signs, which builds coherent complex models

from signs of simple objects.

The true isa measure of the degree of adherence to

reality for a model built by an subject.

The true isa measure of representativeness of the

subject among other subjects for the appreciation of the real object.

The (significant) true model retains the main influences on the real object (modeled, signified) are upon a representative subject.

Simple sentence is an assertion, expressed minimally by reference to a real and concrete action - a predicate (represented by a sign)

applied to an real object - the grammatical topic of the sentence (indicated by another sign).

The sentence is a model of the dynamics of the real object (topic in sentence) under the real action (described by the predicate). Sentences may include other descriptions and explanations of these dynamics.

Judgment is an assignment of truth value to a sentence, the degree of adherence to reality of sentence, as model of the real action on the real object, as is affecting the judging subject.

Judgment of a subject determine, by according value of truth to each sentence,

an order relation in the set of propositions on the same object (about possible predicates, as actions upon the subject)

establishing a true evolution – future prediction – from the subject point of view

for the regarded object dynamic.

Inference is a basic operation to obtaina new judged sentence

from one or more original judged sentences.

Logic is the science of formal thinking which examines the dynamics of complex models

based on the combination of inferences uponobjects as model components.

Semantics (science) is part of semiotics regarding construction of models from signs and their

truth values reflected by the signified reality.

Language is a set of signs called words grouped in lexis and governed by their

lexical rules, grouped into lexical grammar, that build sentences

in accordance with language syntactic rules, grouped into syntactic grammar.

Lexical grammar is a set of logical rules for building signs called words.

Syntactic grammar or syntax, is a set of logical rules for building of judged sentences from

words or simpler judged sentences.

The grammar of a language is a set of logical rules for buildings from words of this language.

The languages are thus logical thinking mechanisms, means of representing rules (invariants deduced from statistical observations) that build new complex models in a particular field of reality (experience gained in that area of reality).

Construction of new models is done by addingto previous models (stored models), new judged statements, deduced from

real experiences directly obtained from direct observations.

Each language is a mechanism for creation, storage, and transmission of new models based ona set of rules designed according to the logic rules

applied to some previous models. Lexis and language rules, as mechanisms of language, are described

through a own superior set of words and a own superior grammar,

grouped in a meta-description languages .

The problem sentence is a new untried sentence relevant to judged like sentences

with actions that cause dissatisfaction to a subject.Solution (to a problem) is a logical construction of judged

sentences, in order to determine the judgment on the untried problem sentence. Solution is the as deduced judged problem sentence.

Abstract problem is the generalization of several like problems, by highlighting invariants.

Abstract problem solution designate “the code" as model of the judgment of abstract problem.

Variable elements of like problems are considered "data" of the abstract problem.

Abstract problems introduce hierarchy in the problem set.Like problems are included in a class

represented by an appropriate abstract problem.

Class hierarchy in problem set is organized by the abstraction degree.

The algorithm is a basic intellectual structure, defined as a solution designed to solve an abstract problem .

An algorithm is built by generalization solving like problems and

is applied to solve other similar problems.

The algorithm retains the "code" solving procedure, the solution, applied to

each particular problem, differentiated each other by "data“.

Elementary intellectual product is a “code” construction from elementary algorithms designed to solve simple concrete like problems, each processing some particular "data", in view to obtain result "data".

Complex intellectual product is a combination of interactive elementary or less complex intellectual products gathered in order to solve a complex concrete like problems.

Intellectual products attached as solutions to a set of judged sentences in a domain, are a starting base to expand, in the problem area adjacent to the yet judged sentences, by performing incremental logic operations, to validate new buildings as solutions to these new problems, obtaining new intellectual products.

The signal is a sign, in the form of an exchange of energy between two systems,

where a system which loses energy, called the transmitter, discloses (signifies) a change in his status

to the system that receives energy, called the receiver. The information it carries a signal is

a measure of the probability of occurrence of signal signified status. When the probability of a state is small, as rare event, the signal signifying

the occurrence of such status information bear much information. Information about a system are obtained by receiving signals from it. In this way, by successively receiving signals, the receiver can build and

maintain a status dynamic model of the transmitter. Models transmit signals in space

The code signals set of a transmission is a complete set of signs represented by a set of signals previously agreed to be exchanged between transmitter and receiver, signs that correspond to words of the corresponding local language grammars.

Grammar of a code signals set is a grammar of the set of signs represented by an agreed code of signals.

A sign code may be subsequently bilateral amended by means of a special signaling mechanism, as a meta-signal language.

The message is a sentence passed by the transmitter to the receiverconsists of signs of the code transmission

governed by grammatical rules of composition. In this way, the transmitter signals to the receiver carries the transmitter

models.

The transmission language is formed by transmission code signals and grammar of that code,

allowing to the transmitter and the receiver a common representation of intellectual products.

Communication convention is an agreement prior transmission between transmitter and

receiver, which establish transmission language. Transmitted signals to the receiver carry information about models and

not about the real state of the systems. The common transmission language uses as lexis the transmission signals

and sentences are called messages. Agreed common transmission language enables the exchange of

compatible models used by the parties and the exchange of solutions for the problems with these models.

Communication System is a means by which signs are transmitted material in space

Memory is a material means by which signs are transmitted in time. Intellectual experience is a set of intellectual products stored,

to their deployment later time possibly for transmission to another location,

as solutions to like problems. Standardized representation of intellectual products through a previously

agreed and stored common language, is a form of representation of these intellectual products, that can find similar problems on the transmitter and receiver

so that the solution found in the transmitter can be applied to the receiver, without creator effort, by copying the

solution. In this way it is possible to transport an intellectual experience, spatial

through signals and temporal by memorizing signs on material media, as signals in time.

The program is a complex intellectual product representationconstrained to a standardized form

transmitted in time by the material memory support transmitted in space by signals

At the destination, in time/space, the new representation (a local copy of the program) start a separate existence, independent by transmitter subject.

The process, the task, is an ongoing on a real machine programexploiting intellectual experience included

for some problem solving, where the program is "code" that process some "data“ characterizing the real problem.

The programs, called applications are software solutions to concrete problems of subjects users aimed at meeting the demands of reality.

Information technology, as an expansion of computer technology is a set of ways, methods and means regarding programs

for them to fulfill their role effectively as providers of solutions to problems solved by program memorized intellectual experience.

Computer technology has evolved to information technology, from the automation of mathematical operations for representation

transmission in time/spacestorage and reproduction outside man,

of complex intellectual products.

Information technology deals withthe “meta processes" which is the process by which programs (software applications) called "code" are

created saved deployed or reproduced to obtain,

outside human in another local space and present in another

time, solutions to problems with "data" local

in that space and present at that time.

The computing machine is a local artifact of computing technology, an information technology implementation, for

creation storing, deployment and reproduction

fast and effective now, in new developments

of application programs.

The computer system is an intellectual "meta product" who activates an intellectual "meta process“ that

solves the problems in the world of intellectual products, regarded as objects.

Components of a computer system, combined to meet the destination specified above, are divided into:

system hardware and

system software components .

Hardware components of a computer system are the means and methods of storage , processing and reproduction of programs ,

characterized by materiality, resistance to the passage of time .

Hardware equipments, or simply hardware are materialized intellectual experience,

Every representation of this experience is a specialized resource, available separately for activities in parallel.

The software components of the system or system software, of a computing system are nonpermanent logical structures that realize methods of using specialized hardware, making them work with their specified embodiments.

Order to use the various but stable H/W resources is determined by the needs of a given algorithm particular, the structure of a program. Different applications may have different orders of use of the same H/W resources in different programs.

Software components , or simply software aresystem software components of a computer system ,dedicated hardware systemThe programs plusimplementing the solution sought by the application.

For the user of a computer system , software generic term designatingthat complex means and methods which arehis specific practical problem solving ,commonly observed that the software packagein its field of interest,that stores experience in solving a wide category of problems similar, but bounded .

The hardware is perceived as a support material , devices and mechanical assemblies , electrical , magnetic, and so on , establishing a common equipment for all applications running , which interact to perform processing operations or inputs and outputs.

Programs aiming system activation, management and optimization of resource materials for use with application programs . System programs are so related to material support that appear virtually unchanged from that party software that identifies all applications in different domains running on the same hardware specific . System programs are divided into system utilities and operating systems .

The activity of a computer system is centered programs for storage, processing and reproduction which provide means and methods computers .

The classic version of von Neumann computing machines , as its activity is handling structures "data" ,

processed by interactive processesgenerated by the implementation of programs,consist of lists of lines "code"appropriate for these structures ."Data " are possible values for an organized information about application , suffering possible

changes during processingand " code " is a program that includes some of the intellectual experience necessary to solve

the problem for the set of "data" custom ."Code" is considered immutable , does not change during processing program, but can be

chosen during processing from multiple pre-while " data " can bedifferent from one run to another at the beginning of processing ,can handle changes during processing andmaterialize solution to the problem ."Data " are organized into several specialized forms called " data structures " (cells , tables,

stacks , lists, etc.). Adapted to certain repetitive manipulation algorithms .

Software engineering isa collection of methods and procedures by whichdeveloping solutions to problems through programs as criteria is metquality andefficiency.The functional paradigm for software development, software engineering conformity ,developers 'code' is the direct processing ofentities "data" in order tofulfill the purpose of making an application.model of reality is represented separately from the programdesigner's imagination andAccess to "date" is exposed.In object oriented paradigm for software development , software engineering compliant ,reality is first simulated computer systemby a model with separate existence , whichreplace real objects"Objects" component of the model become "code" .The model processing is performed in accordance problemand the results are then transferred back into reality as solutions .Access to "data" , understood as a state of "objects " of the model components is mediated processes and

protected access to their own state , enabled by access mechanisms that equip " items " taken from the interface mechanisms object model.

The paradigm of object oriented approach to the development of complex and dynamic applications has advantages of flexibility and adaptability , optimizing maintenance, modification or reuse programs .

In conclusion,

Computers and information technology became composed of hardware and System software, is a reproduction frame, processing and preservation of intellectual products, providing a temporal propagation environment and space of solutions called applications. In this way, the experience gained by testing statistical local awareness of order in

nature, is provided and become active global spatial and temporal thereafter. Calculating machines, managed, understandable by the operating system, is used to development and maintenance of applications running in system utilities to obtain concrete solutions to new problems more complex.