Q1. What is device driver? OR Use of driver software. Ans. A device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device. A driver typically communicates with the device through the computer bus or communications subsystem to which the hardware connects. When a calling program invokes a routine in the driver, the driver issues commands to the device. Once the device sends data back to the driver, the driver may invoke routines in the original calling program. Drivers are hardware-dependent and operating-system-specific.
Uses of device driver:
a. A device driver simplifies programming by acting as a translator between a hardware device and the applications or operating systems that use it. Programmers can write the higher-level application code independently of whatever specific hardware device it will ultimately control, because code and device can interface in a standard way, regardless of the software superstructure or of underlying hardware b. The device-driver accepts these generic high-level commands and breaks them into a series of low-level device-specific commands as required by the device being driven. c. Drivers can provide a level of security as they can run in kernel-mode thereby protecting the operating system from applications running in user-mode.

SECTION - B ( 5 MARKS )

Q1. Describe the problem that occur when you attempt when you attempt to connect together two RS-232-C devices that are both configured as DTE. Draw a diagram which shows how this problem can be solved. Ans. The wiring of RS232 has always been a problem. Originally the standard s defined for DTE, Data terminal equipment to DTE, data communication equipment connection, b soon people started to use the communication interface to connect two DTEs directly using null modem cables. No standard was defined for null modem connections with RS232 and not long after their introduction, several different wiring schemes became common. With DEC Connect, Digital Equipment Corporation tried to define their own standard for serial interconnection of computer device with MMJ modifier modular jack connectors. This interfacing standard became available on most of their hardware, but it wasn’t adopted by other computer manufactures. May be because DEC used as non-standard version of the modular jack. UTP and FTP cables with RJ45 connectors became the de-facto — standard in office cabling systems, and people started looking for the ways to transmit RS232 signals over these cabling systems. The RS 232D standard was the official attempt for a standard to transmit RS232 over RJ45.Unfortunately this attempt didn’t twist the cable internally. This is primary remained a standard for DTE to DCE connection in a world where the primary use of RS232 was to interconnect DTEs directly. Goals of the Wiring Standard The mess with RS232 wiring is widely known. It was the reason for starting this website. Dave Yost wanted to solve that mess once and for all, reaching as much as possible of the following goals:
All cable connectors should have the same connector type(RJ45)

The goals are very close to goals DEC wanted to achieve with DEC Connect. The Yost standard has however one basic advantage. Because RJ45 connectors are used, eight pins are available which makes it possible to transfer almost all RS232 signals. Therefore the Yost standard can be used with much more equipment than DEC Connect.

Q2. Write the short note on USB. Ans. USB is short for Universal Serial Bus, an external bus standard that supports data transfer rates of 12 Mbps. Many computers will even have additional USB ports located on the front of the tower, in additional to two standard USB ports at the back. In the late 1 990s, a few computer manufacturers started including USB support in their new system but today USB has become a standard connection port for many devices such as keyboards, mice, joysticks and digital cameras to name but a few USB enabled devices. USB is able to support and is supported by a large range of products. Adding to the appeal of USB is that it is supported at the operating system level, and compared to alternative ports such as parallel or serial ports USB is very user-friendly. When USB first started appearing in the marketplace, it was (and still is) referred to as a plug-and-play port because of its ease of use. Consumers without a lot of technical or hardware knowledge were able to easily connect USB devices to their computer. You no longer needed to turn the computer off to install the devices either. You simply plug them in and go. USB devices can also be used across multiple platforms. USB works on Windows and M plus can be used with other operating systems, such as Linux for example, with a reliable degree of success. Before USB, connecting devices to your system was often a hassle. Modems and digital cameras were connected via the serial port which was quite slow, as only I bit is transmitted at a time through a serial port. While printers generally required a parallel printer port, which is able to receive more than one bit at a time — that is, it receives several bits in parallel. Most systems provided two serial ports and a parallel printer port. If you had several devices, unhooking one device and setting up the software and drivers to use another device could often be problematic for the user. The introduction of USB ended many of the headaches associated with needing to use serial ports and parallel printer ports. USB offered consumers the option to connect up to 127 devices, either directly or through the use of a USB h It was much faster since USB supports data transfer rates of 12 Mbps for disk drives and other high-speed throughput and 1.5Mbps for devices that need less bandwidth.
Additionally, consumers can literally plug almost any USB device into their computer, and Windows will detect it and automatically set-up the hardware settings for the device. Once that device has been installed you can remove it from your system and the next time you plug it in,
Windows will automatically detect it. USB 1x First released in 1996, the original USB 1.0 standard offered data rates of
1.5 Mbps. The USB 1.1 standard followed with two data rates: 12 Mbps for devices such as disk drives that need high-speed throughput and 1.5
Mbps for devices such as joysticks that need much less bandwidth. USB 2.0
Also referred to as Hi-Speed USB, USB 2.0 is an external bus that supports data rates up to 480Mbps. USB 2.0 is an extension of USB 1.1. USB OTG
Short for USB On-The-GQ, an extension of the USB 2.0 specification for connecting peripheral devices to each other. USB OTG products can communicate with each other without the need to be connected to a PC. Types of USB Connectors
Currently, there are four types of USB connectors: Type A, Type B, mini-
A and mini-B and are supported by the different USB specifications
(USB 1, USB 2 and USB-OTG).

Often referred to as the downstream connector, the Type A USB connector is rectangular in shape and is the one you use to plug into the CPU or USB hub.

Also called the upstream connector, the Type B USB connector is more box-shaped and is the end that attaches directly to the device (such as a printer or digital camera).

SECTION - C ( 10 MARKS )

Q1. Discuss the DOS and UNIX device drivers in detail. OR
Explain the features of UNIX device driver. OR
Write Short Note on UNIX device drivers. OR
Write short notes on UNIXILINUX device drivers. OR
Explain in brief the role of device drivers in DOS and LINUX/UNIX. Ans. A device driver is a program that allows hardware devices to communicate with a computer. Device drivers plug into the operating system and enable the operating system to provide you and your application programs with access to that hardware. DOS Device drivers: Dos is quite simple to describe, since it principally consists of only four parts:

When we talk about hardware control, it is done IO.SYS. That is a program which reads ROMN BIOS code a convert it to DOS’s own device drivers. The smart thing about DOS is that the operating system can be expanded with external device drivers. IO.SYS reads them via the startup file CONFIG.SYS. First device drivers are read from ROM-BIOS. Then any possible additional drivers are read from disk. In that way DOS can handle hardware units which did not exist when the PC was originally configured. A final option to handle hardware from DOS programs is to write special drivers for the individual user programs. Many DOS games come with their own graphics drivers (they have to recognize all graphic on the market). Another classic example is the word processing program W which An illustrated guide to operating system and the use of hard ware drivers in its prime(version 5.1) came with drivers to more than 500 different printers.

Q2.Explain DOS services for Diskette and keyboard. Ans. Application programs running under DOS have system privileges. They can access any storage, change the CPU control functions, and use any hardware device. This allows some programs to extend the DOS operating system with additional functions, but it also allows virus programs to damage the machine. Although DOS 6.x is distributed on 4 or 5 disks, this space is filled with utility programs to compress data, perform backups and check programs for virus infection. The DOS operating system itself is contained in a pair of hidden files named as IBMBIO.SYS and IBMDOS.SYS .DOS services are requested when an application program issues an INT2 I instruction . This instruction looks up the entry point of the DOS service manager in a hardware table and jumps to a routine in the IBMDOS module. In other operating systems, an application must make a system call to request services. DOS application programs run with full privilege, so a program can do anything it wants if it has enough program logic to handle the hardware directly. BIOS provide keyboard service routine under into 1611, here we describe 3 common routine that are useful in accessing the keyboard. As with the DOS functions, the AM register should contain the function code before executing an interrupt of type I6FLOne difference between DOS and BIOS functions is that if you u DOS services, the keyboard input can be redirected.

Q4. What is the primary purpose a device driver? Explain UNIX/LINUX device drivers in detail. Ans. A device driver is a file that lets the computer know the configuration and specifications of a certain hardware device. Some examples of devices that need drivers are hard drives, DVD drives, and PCI cards. Without the driver file, the computer will be unable to communicate with the device. Often, Windows will alert the user if there is a new device which doesn’t have a driver installed yet. It will then hopefully let you install the correct driver for it. “Hopefully” being the key word. Types of Device Drivers
A device driver is a software module that resides within the Digital UNIX kernel and is the software interface to a hardware device or devices. A hardware device is a peripheral, such as a disk controller, tape controller, or network controller device. In general, there is one device driver for each type of hardware device. Device drivers can be classified as:

Applications
Because of the diversity of modern hardware and operating systems, drivers operate in many different environments. Drivers may interface with:

Common levels of abstraction for device drivers include: for hardware:

Choosing and installing the correct device drivers for given hardware is often a key component of computer system configuration.
UNIX/LINUX device drivers