1) Explain the main purpose of
an operating system?
Operating systems exist for two main purposes. One is that it is
designed to make sure a computer system performs well by managing its
computational activities. Another is that it provides an environment for the
development and execution of programs.
2) What are real-time systems?
Real-time systems are used when rigid time requirements have
been placed on the operation of a processor. It has well defined and fixed time
constraints.
3) What is virtual memory?
Virtual memory is a memory management technique for letting
processes execute outside of memory. This is very useful especially is an
executing program cannot fit in the physical memory.
4) Describe the objective of multiprogramming.
The main objective of multiprogramming is to have process
running at all times. With this design, CPU utilization is said to be
maximized.
5 ) What are time sharing systems?
In a Time sharing system, the CPU executes multiple jobs by
switching among them, also known as multitasking. This process happens so fast
that users can actually interact with each program while it is running.
6) What is SMP?
SMP is short for Symmetric MultiProcessing, and is the most
common type of multiple-processor systems. In this system, each processor runs
an identical copy of the operating system, and these copies communicate with
one another as needed.
7) Give an example of a Process
State.
– New State – means a process is being created
– Running – means instructions are being executed
– Waiting – means a process is waiting for certain conditions or events to occur
– Ready – means a process is waiting for an instruction from the main processor
– Terminate – means a process is done executing
– Running – means instructions are being executed
– Waiting – means a process is waiting for certain conditions or events to occur
– Ready – means a process is waiting for an instruction from the main processor
– Terminate – means a process is done executing
8) What is demand paging?
Demand paging is a system wherein area of memory that are not
currently being used are swapped to disk to make room for an application’s
need.
9) What are the advantages of a multiprocessor system?
With an increased number of processors, there is considerable
increase in throughput. It can also save more money because they can share
resources. Finally, overall reliability is increased as well.
10) What is kernel?
Kernel is the core of every operating system. It connects
applications to the actual processing of data. It also manages all
communications between software and hardware components to ensure usability and
reliability.
11) What is a socket?
A socket provides a connection between two applications. Each
endpoint of a communication is a socket.
12) What is Direct Access Method?
Direct Access method is based on a disk model of a file, such
that it is viewed as a numbered sequence of blocks or records. It allows
arbitrary blocks to be read or written. Direct access is advantageous when
accessing large amounts of information.
13) When does thrashing occur?
Thrashing refers to an instance of high paging activity. This
happens when it is spending more time paging instead of executing.
14) What is the best page size when designing an operating system?
The best paging size varies from system to system, so there is
no single best when it comes to page size. There are different factors to
consider in order to come up with a suitable page size, such as page table,
paging time, and its effect on the overall efficiency of the operating system.
15) When designing the file structure for an operating system,
what attributes are considered?
Typically, the different attributes for a file structure are
naming, identifier, supported file types, and location for the files, size, and
level of protection.
16) What is root partition?
Root partition is where the operating system kernel is located.
It also contains other potentially important system files that are mounted
during boot time.
17) What are device drivers?
Device drivers provides a standard means of representing I/O
devices that maybe manufactured by different companies. This prevents conflicts
whenever such devices are incorporated in a systems unit.
18) What are the primary functions of VFS?
VFS, or Virtual File System, separates file system generic
operations from their implementation by defining a clean VFS interface. It is
also based on a file-representation structure known as vnode, which contains a
numerical designator needed to support network file systems.
19) What are the different types of CPU registers in a typical
operating system design?
– Accumulators
– Index Registers
– Stack Pointer
– General Purpose Registers
– Index Registers
– Stack Pointer
– General Purpose Registers
20) What is the purpose of an I/O status information?
I/O status information provides info about which I/O devices are
to be allocated for a particular process. It also shows which files are opened,
and other I/O device state.
21) What is multitasking?
Multitasking is the process within an operating system that
allows the user to run several applications at the same time. However, only one
application is active at a time for user interaction, although some
applications can run “behind the scene”.
22) What are some pros and cons of a command line interface?
A command line interface allows the user to type in commands
that can immediately provide results. Many seasoned computer users are well
accustomed to using the command line because they find it quicker and simpler.
The main problem with a command line interface is that users have to be familiar
with the commands, including the switches and parameters that come with it.
This is a downside for people who are not fond of memorizing commands.
23) What is caching?
Caching is the processing of utilizing a region of fast memory
for a limited data and process. A cache memory is usually much efficient
because of its high access speed.
24) What is spooling?
Spooling is normally associated with printing. When different
applications want to send an output to the printer at the same time, spooling
takes all of these print jobs into a disk file and queues them accordingly to
the printer.
25) What is an Assembler?
An assembler acts as a translator for low level language.
Assembly codes, written using mnemonic commands are translated by the Assembler
into machine language.
26) What are interrupts?
Interrupts are part of a hardware mechanism that sends a
notification to the CPU when it wants to gain access to a particular resource.
An interrupt handler receives this interrupt signal and “tells” the processor
to take action based on the interrupt request.
27) What is GUI?
GUI is short for Graphical User Interface. It provides users
with an interface wherein actions can be performed by interacting with icons
and graphical symbols. People find it easier to interact with the computer when
in a GUI especially when using the mouse. Instead of having to remember and
type commands, users just click on buttons to perform a process.
28) What is preemptive multitasking?
Preemptive multitasking allows an operating system to switch
between software programs. This in turn allows multiple programs to run without
necessarily taking complete control over the processor and resulting in system
crashes.
29) Differentiate logical from
physical address space.
Logical address refers
to the address that is generated by the CPU. On the other hand, physical
address refers to the address that is seen by the memory unit.
30) How does dynamic loading aid in
better memory space utilization?
With dynamic loading,
a routine is not loaded until it is called. This method is especially useful
when large amounts of code are needed in order to handle infrequently occurring
cases such as error routines.
31) What are overlays?
Overlays are used to
enable a process to be larger than the amount of memory allocated to it. The
basic idea of this is that only instructions and data that are needed at any
given time are kept in memory.
32) What is the basic function of
paging?
Paging is a memory
management scheme that permits the physical-address space of a process to be
noncontiguous. It avoids the considerable problem of having to fit varied sized
memory chunks onto the backing store.
33) What is fragmentation?
Fragmentation is
memory wasted. It can be internal if we are dealing with systems that have
fixed-sized allocation units, or external if we are dealing with systems that
have variable-sized allocation units.
34) How does swapping
result in better memory management?
During regular intervals that are set by the
operating system, processes can be copied from main memory to a backing store,
and then copied back later. Swapping allows more processes to be run that can
fit into memory at one time.
35) What factors determine
whether a detection-algorithm must be utilized in a deadlock avoidance system?
One is that it depends on how often a deadlock is likely to
occur under the implementation of this algorithm. The other has to do with how
many processes will be affected by deadlock when this algorithm is applied.
10) How are server systems
classified?
Server systems can be classified as either computer-server
systems or file server systems. In the first case, an interface is made
available for clients to send requests to perform an action. In the second
case, provisions are available for clients to create, access and update files.
36) What is asymmetric clustering?
In asymmetric clustering, a machine is in a state known as hot
standby mode where it does nothing but to monitor the active server. That
machine takes the active server’s role should the server fails.
37) What is a thread?
A thread is a basic unit of CPU utilization. In general, a
thread is composed of a thread ID, program counter, register set and the stack.
38) Give some benefits of multithreaded programming.
– there is an increased responsiveness to the user
– resource sharing within the process
– economy
– utilization of multiprocessing architecture
– resource sharing within the process
– economy
– utilization of multiprocessing architecture
39) Briefly explain FCFS.
FCFS is short for First-come, first-served, and is one type of
scheduling algorithm. In this scheme, the process that requests the CPU first
is allocated the CPU first. Implementation is managed by a FIFO queue.
40) What is RR scheduling algorithm?
RR (round-robin) scheduling algorithm is primarily aimed for
time-sharing systems. A circular queue is setup in such a way that the CPU
scheduler goes around that queue, allocating CPU to each process for a time
interval of up to around 10 to 100 milliseconds.
41) What necessary conditions can lead to a deadlock situation in
a system?
Deadlock situations occur when four conditions occur
simultaneously in a system: Mutual exclusion; Hold and Wait; No preemption; and
Circular wait.
42) Enumerate the different RAID levels.
RAID 0 – Non-redundant striping
RAID 1 – Mirrored Disks
RAID 2 – Memory-style error-correcting codes
RAID 3 – Bit-interleaved Parity
RAID 4 – Block-interleaved Parity
RAID 5 – Block-interleaved distributed Parity
RAID 6 – P+Q Redundancy
RAID 1 – Mirrored Disks
RAID 2 – Memory-style error-correcting codes
RAID 3 – Bit-interleaved Parity
RAID 4 – Block-interleaved Parity
RAID 5 – Block-interleaved distributed Parity
RAID 6 – P+Q Redundancy