Assignment On Operating Systems-1

Running head: OPERATING SYSTEMS
OPERATING SYSTEMS
Name of the Student
Name of the university
Author note

1OPERATING SYTEMS
I/O devices
I/O and processing can be considered as the major jobs from the perspective of
computer system.
An operating system plays a major role in the context of I/O in a computer that is managing
as well as controlling the various operations like I/O and the input-output devices. Computer
systems involve in operation of different types of devices and the common examples of
devices which are used for storage include human interface devices, transmission devices and
disks. Transmission devices include network interface cards and other device such as
modems while the human interface devices include screen, keyboard and many more
(Tanenbaum & Bos, 2015). Management of I/O devices are important because this form the
main elements of a computer system, the input device sending information to the computer
for the purpose of processing while an output device is there to reproduce or to display the
results of the input that has been processed.
Device drivers can be defined as software modules which are plugged into the
operating system for the purpose of handling a specific device. Operating system can be said
to take the help of these device drivers for the purpose of handling all the I/O devices (Chen,
Wu, Shao, Lockerman & Gu, 2016). Device driver is recorded by the manufacturer of a
device and is included in the device with the help of a CD-ROM.
Polling
One of the simplest ways in which communication occurs between an I/O device and
processor is known as polling. This refers to the process that includes periodical checking
device’s status in order to check if the next I/O operation can be done. The work of I/O
device in this case is to put the data in the register concerned with the status and thereafter
information is collected by the processor. It can be said that mostly the devices do not require

2OPERATING SYTEMS
any such attention but when any device requires it has to wait until the polling program
interrogates it. This makes the process inefficient as time of the processor is wasted on the
unnecessary polls. In order to understand the polling process handshaking needs to be
understood considering an example. Suppose 2 bits are made use of for bringing in
coordination in between the controller and the host. In order to indicate its status, the
controller makes use of the busy bit in status register (Silberschatz, Galvin & Gagne, 2014).
To show its status of working, when busy the controller sets the busy bit and clears the same
when ready to work with the new command. The ready bit command is set by the host when
command execution has to be done by a controller. Busy bit is read by the host set by the
controller until the bit becomes empty and this is what called polling.
Interrupts
The interrupt-driven method is considered as an alternative scheme that can be made
use of to deal with I/O. Specifically, an interrupt can be said to a signal given to the
microprocessor from any device that needs much attention. It is the work of the device
controller to interrupt a signal on to bus during the time it requires the attention of the CPU.
After the CPU receives an interrupt, the present state of the same is saved and at the same
time appropriate interrupt handles is invoked by making use of interrupt vector. Once dealing
with the device that was interrupting, CPU continues with the original task that it was doing
and it seems as if it had never encountered any interruption in its work. Thus it can be said
that interrupt I/O are ways in which the various I/O activities are controlled. In this process a
peripheral requiring making or receiving data transfer sends signal causing a program to
interrupt so that it gets set (Wang, Wang, Shaving & Vehicle-to-Grid, 2013). An ISR or
interrupt service routine is entered by the processor at an appropriate time, the parameter
being level of priority in the I/O interrupt. The routine’s function depends on the interrupt
levels of system as well as the priorities that have been implemented in processor. An