Topologia

IBM
Guía de estudio
Fecha de elaboración:
27/11/2005

INFORMATICA INTEGRAL
EMPRESARIAL, S.A. DE C.V.

1. Software Engineering
a. Operating Systems
Operating Systems Components.
Even though, not all systems have the same structure many modern operating systems share the
same goal of supporting the following types of system components.
Process Management.
The operating system managesmany kinds of activities ranging from user programs to system
programs like printer spooler, name servers, file server etc. Each of these activities is encapsulated
in a process. A process includes the complete execution context (code, data, PC, registers, OS
resources in use etc.).
It is important to note that a process is not a program. A process is only ONE instant of a program inexecution. There are many processes can be running the same program. The five major activities of
an operating system in regard to process management are:
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Creation and deletion of user and system processes.
Suspension and resumption of processes.
A mechanism for process synchronization.
A mechanism for process communication.
A mechanism for deadlock handling.

Main-MemoryManagement
Primary-Memory or Main-Memory is a large array of words or bytes. Each word or byte has its own
address. Main-memory provides storage that can be access directly by the CPU. That is to say for a
program to be executed, it must in the main memory. After the processor is the most expensive
resource in the system, it’s volatile, fast and always less than secondary storage or secondary
memory.The major activities of an operating in regard to memory-management are:
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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.

File Management
A file is a collected of related information defined by its creator. Computer can storefiles on the disk
(secondary storage), which provide long term storage. Some examples of storage media are
magnetic tape, magnetic disk and optical disk. Each of these media has its own properties like
speed, capacity, data transfer rate and access methods.
Elaboró:
Alfonso Fco. Garcia Hdez. – Gerente de Tecnología

Fecha Emisión:
28/11/05

Hoja: 1 De 76

IBM
Guía de estudio
Fechade elaboración:
27/11/2005

INFORMATICA INTEGRAL
EMPRESARIAL, S.A. DE C.V.

The five main major activities of an operating system in regard to file management are
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The creation and deletion of files.
The creation and deletion of directions.
The support of primitives for manipulating files and directions.
The mapping of files onto secondary storage.
The back up of fileson stable storage media.

I/O System Management
I/O subsystem hides the peculiarities of specific hardware devices from the user. Only the device
driver knows the peculiarities of the specific device to which it is assigned.

Secondary-Storage Management
Generally speaking, systems have several levels of storage, including primary storage, secondary
storage and cache storage. Instructionsand data must be placed in primary storage or cache to be
referenced by a running program. Because main memory is too small to accommodate all data and
programs, and its data are lost when power is lost, the computer system must provide secondary
storage to back up main memory. Secondary storage consists of tapes, disks, and other media
designed to hold information that will eventually beaccessed in primary storage (primary,
secondary, cache) is ordinarily divided into bytes or words consisting of a fixed number of bytes.
Each location in storage has an address; the set of all addresses available to a program is called an
address space.
The three major activities of an operating system in regard to secondary storage management are:
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Managing the free space available on...