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A(n) operating system is
- a set of system software
- routines that sits between the application program and the hardware. It defines
- a set of standard interface rules, provides numerous services, and serves as a
- platform for running and developing application programs.
A(n) interface is
- a point of connection or linkage between two
When the user communicates
directly with the hardware it is not an example of a
All application programs
access the hardware ______ the operating system following
rules imposed___ the operating system
A(n) service is
- a software routine that
- runs in support of another program.
Because different brands of computers often
imply different hardware, the operating system routines that communicate
directly with the hardware might be quite different, but the routines that
interface with the application program present a
consistent platform tothe programs running on both machines.
The advantage of using layers
of abstraction is
- that you can focus on the
- details of any given component without losing sight of the other component.
The idea behind viewing a
system as a set of layers of abstraction is
- derived from an old
- architectural concept called layering.
The contents of a black
- unknown to the other
- boxes, so each black box is functionally independent.
Two black boxes
communicate with each other
- only through a shared interface or point of
The current program and the current data
- must be stored in memory before the computer can
- manipulate the data.
a byte is
On most computers, the basic addressable unit of memory
When you read memory, you do not change the
contents. When you write memory you
destroy the old contents.
Most computer memory is
ROM can be read, but not
A byte contains enough bits (usually eight) to
represent a single character
Most computers are able to manipulate a group of bytes
- a word that often holds a single number.
To distinguish them, each byte (more generally, each
physical storage unit) is assigned a
Data moves between the processor and memory
one byte or one word at a time.
One way to increase processing speed is to move program
instructions and data from memory to the processor more quickly. To help
accomplish this objective, many computers
contain a block of high-speed cache memory.
A computer is a machine
- processes data under
- control of a stored program
In a program, each instruction
- tells the computer to perform one of its basic
A typical instruction
contains an operation code that specifies the function to be performed and one
or more operands that specify
- the memory locations or
- registers that hold the data to be manipulated.
A program stored in memory
in binary form.
Hardware works with absolute
addresses, fetching and storing the contents of individual bytes by referencing
A relative address is an
address expressed relative to some
The process of converting
a relative address to an absolute address is called
- dynamic address
An assembler program reads
a programmer’s source code and produces
a(n) object module.
An assembler language
programmer writes one mnemonic instruction for each
With a compiler, a given
source statement may be converted to any number of
A computer’s internal components are physically linked
- bus, a ribbon-like set of electrical lines (or wires)
- that carries several bits at a time, in parallel.
Many personal computers feature a local I/O bus that
follows the PCI (peripheral component interconnect) standard and a slower
ISA (industry standard architecture) bus.
On most systems the internal components are designed
a common word size.
Memory capacity is not affected by
a computer’s word size
On a small computer, it is possible to gain memory
A computer’s memory capacity is a function of its
A 16-bit machine can access more than 64 KB if addresses are
- broken into two or more parts and transmitted during
- successive machine cycles.
During I-time, the instruction control unit
fetches the next instruction from memory.
A register called the instruction counter points
- 1. to the computer’s next
During E-time, the arithmetic and logic unit executes
the instruction stored in the
The user interface provides
a mechanism for the system operator and the user to
- communicate with the
- operating system and request operating system services.
The file system incorporates
routines that allow the user or programmer to
- create, delete, modify,
- and manipulate files by name.
Memory management is
- managing the system’s memory resources,
- allocating space to applications as needed and ensuring that those applications
- do not interfere with each other.
An application program transparently requests operating
system services through an
application programming interface (API).
A system operator or a user identifies the program to be
- issuing one or more commands directly to the operating
The operating system’s user interface
accepts, interprets, and carries out commands.
A user communicates with a command
line interface or shell by
- typing brief, cryptic
A menu interface presents
- the user with a list of
- available options.
The Apple Macintosh and
Microsoft Windows both feature a graphical user interface (GUI) that presents
the user with
- a selection of windows, icons, and
Several different user
- coexist on the same