OS topic 13 – Input/output Flashcards
What is a device driver?
A device driver is a piece of s_________ that allows your computer’s operating system to communicate and work with hardware devices.
It serves as a t__________ between the __________________ and the specific hardware, helping them understand each other.
software
translator
operating system
Device Drivers
When you connect a new hardware device to your computer, like a printer or a graphics card, the device driver enables the operating system to s_____ and r_______ data to and from that device.
send and receive
Device Drivers
True or false
Without device drivers, your computer wouldn’t be able to use or control the connected hardware properly.
True
Device Drivers - Problem
Device drivers run in k_______ mode with access to c_______ operating system data; if a driver has b______, then it may well crash the entire system.
kernel mode
critical OS data
bugs
Device Drivers - Problem
Why might a commercial OS may restrict installation to drivers that have been appropriately signed after passing thorough testing.
To avoid damage to their reputation.
As mentioned earlier, a buggy driver can crash the entire system!!!
Bus interfaces
What is a bus?
A bus is an i___________ to which several devices can be connected at the same time.
interface
Bus interfaces
What are ‘data transfer protocols’
Data transfer protocols are sets of rules and conventions that define how data is e___________ between devices or systems over a n__________.
exchanged
network
Bus interfaces
What data transfer protocols are usually used by buses?
There are many, but one example is
PCI (P___________ C__________ I_____________):
PCI is a standard bus protocol used for communication between internal components in a computer, such as graphics cards, network cards, and storage devices. It supports high-speed data transfer.
Peripheral Component Interconnect
Bus Interfaces
A bus is an interface to which several devices can be connected at the same time; this requires s_______________ data transfer protocols and a way of identifying different devices.
standardised
Bus Interfaces
The data transfer protocols are implemented through a s_____ of software routines.
stack
Bus Interfaces
What is meant by ‘a stack of software routines’?
A “stack of software routines” typically refers to a collection or s________ of software routines, where each routine represents a specific set of instructions or operations that perform a particular task.
The term “stack” is often used metaphorically to describe the o__________ or arrangement of these routines in a h___________ manner.
sequence
organisational
hierarchical manner
Bus Interfaces
Bus-connected devices need to i_____________ themselves so that they are treated appropriately.
USB, for example, allows each peripheral to describe itself to the host computer when first plugged in.
identify themselves
Bus Interfaces
True or false
An example of how the device describes itself could be: Audio, video, etc.
True
Bus Interfaces
There is also a configuration phase where for example the host computer and peripheral device negotiate d_____ rates and, if necessary, a specialised driver is located and loaded into the k______.
data rates
kernel
Bus Interfaces
True or false?
A bus such as USB, as well being used to connect devices, must also be thought of as an I/O device in its own right.
True
Bus Interfaces - The major and minor numbering system
The major and minor numbering system is a convention used in operating systems (OS) to identify and manage different d_______ or resources, particularly in the context of device drivers.
devices
Bus Interfaces - The major and minor numbering system
Devices receive a major and a minor device number when the system b________:
Devices receive a major and a minor device number when the system boots:
Bus Interfaces - The major and minor numbering system
Each different type of device gets a new major number, but two devices of the s______ type share a major number and have different minor numbers.
same type
One major classification used by most OSs is into character and block devices.
What classification would a keyboard be?
What classification would a disk drive be?
Keyboards generate a stream of characters, as do mice, and these can be handled one byte (or character) at a time.
Other devices, for example secondary storage such as disk drives, always transfer data in large fixed-size blocks.
The hardware interface
I/O registers provide the lowest-level interface to hardware, and typically have three different roles:
- d_______ register:
- s__________ register:
- c__________ register:
data
status
control
The hardware interface - I/O registers
The data register
It holds the data that is to be t___________
transferred
The hardware interface - I/O registers
The status register
Indicate for example whether more data is w___________ to be collected or whether the I/O device is b_______ and cannot yet accept more data.
waiting
busy
The hardware interface - I/O registers
The controls register
Set o________, for example whether data is to be read from or written to the device.
options
Data Transfers - Polled I/O
There are _________ techniques used to control the transfer of data between m______ memory and an I/O device
three
main memory
Data Transfers - Polled I/O
Poll the device: In this context, “polling” means that the processor regularly c_______ or q______ the I/O device to see if there is any new information or if a specific event has occurred.
checks or queries
Data Transfers - Polled I/O
One technique used to control the transfer of data between main memory and an I/O device is for the processor to p____ the device until an I/O event occurs.
poll
Data Transfers - Polled I/O
Polling is a useful technique in complex systems.
False
Polling is a useful technique in simple embedded systems
Data Transfers - Polled I/O
There are problems using it in a personal computer. The main problem is that it uses busy waiting: the processor is t____ up until I/O is complete.
True or false?
In a multitasking system it would be better for a context switch to occur so that another process can be executed while the I/O is in progress.
A further problem is that it is difficult to deal with multiple I/O devices: the polling l____ would have to check every possible device and be executed frequently so that no events are missed.
tied up
True
loop
Data Transfers - Interrupt-driven I/O
Interrupt-driven I/O is much better suited to the needs of a personal computer than polling, because there is no b_____ w______:
the processor is never tied up in l_____ while waiting for slow I/O devices, so overall p__________ of a system can be much better.
busy waiting
loops
performance
Data Transfers - Interrupt-driven I/O
True or false?
With interrupt-driven I/O, the OS hardware signals an interrupt whenever an I/O operation is completed;
that is whenever an input arrives, or an output operation finishes and the device is ready for another operation.
False
The I/O hardware signals an interrupt.
Data Transfers - Interrupt-driven I/O
Interrupt-driven I/O is much better suited to the needs of a personal computer than polling because There is no busy waiting:
Data Transfers - Interrupt-driven I/O
True or false?
There is an overhead in handling each interrupt.
True
Data Transfers - Direct memory access I/O
A direct memory access (DMA) controller is a device that can transfer data directly between _______ devices and main memory without involving the p___________.
I/O
processor
Data Transfers - Direct memory access I/O
The DMA controller itself is a device with its own I/O r_________ that the operating system can use to specify what transfer is to be made.
registers
