AS Computer Science 9618: Device Drivers and Peripheral Management

A small design studio buys a new graphics tablet, a peripheral device that lets an artist draw directly onto the screen instead of using a mouse. When the tablet is first connected to a computer, the operating system cannot yet control it correctly, until a particular piece of software for that specific tablet has been installed.

(a) State the name given to this piece of software. [1]

(b) Explain why the operating system cannot simply send the same, generic commands directly to every different peripheral device without this software installed. [2]

(c) A different employee at the studio owns a completely different make of graphics tablet, used on their own computer. Explain why the software installed for the studio's first tablet would not work correctly for controlling this different make of tablet. [2]

(d) Explain one way the operating system's hardware and peripheral management makes it easier for application software, such as a drawing program, to work with many different makes of graphics tablet. [2]

Part (a): Naming the software

The piece of software the operating system needs, written for this specific peripheral device, is a device driver. [1 mark] for correctly naming it.

Part (b): Why generic commands are not enough

Every different type of peripheral device is built differently and works in its own specific way, so it needs its own specific set of low-level control signals to make it do anything useful. A command that correctly controls one type of device might not be understood at all by a completely different type of device, or might make it behave incorrectly. A device driver exists to bridge this gap: it translates the generic requests the operating system and application software make (such as “read the pen’s position”) into the exact, specific signals that particular device needs to receive. [2 marks]: [1] for stating that different devices need different specific control signals, [1] for explaining that the driver translates a generic request into these device-specific signals.

Part (c): Why a driver is device-specific, not just device-category-specific

Although both peripherals are graphics tablets, two different makes are built with different internal hardware and firmware, and so expect a different set of specific control signals from the computer, even for the same basic action such as reporting the pen’s position. A device driver is written to match the exact commands understood by one particular device. Because it was written for the studio’s first tablet, it has no knowledge of the different specific commands the other make of tablet requires, so it cannot reliably control that different device. [2 marks]: [1] for recognising that different makes expect different specific control signals, [1] for explaining that the driver is matched to one particular device and so cannot control a different make.

Part (d): Why this makes life easier for application software

Hardware and peripheral management, through device drivers, lets application software such as a drawing program deal only with a generic, standard request (for example, “get the pen’s current position”) rather than needing to know the low-level detail of how every individual make of tablet actually works. The correct device driver for whichever tablet is connected converts this generic request into that specific device’s own commands behind the scenes. This means the same drawing program can work correctly with many different makes of graphics tablet, as long as an appropriate driver has been installed for each one, without the drawing program itself needing to be rewritten for every different device. [2 marks]: [1] for explaining that application software only needs to make a generic request, [1] for explaining that the device driver handles the device-specific translation, allowing one program to work with many makes of device.

Final answers

(a) A device driver.
(b) Different devices need different specific control signals; the driver translates the operating system’s generic requests into these device-specific signals.
(c) Different makes of tablet expect different specific signals; a driver is matched to one particular device, so it cannot correctly control a different make.
(d) Application software makes only a generic request; the installed device driver translates it into that specific device’s own commands, so one program can work with many makes of device.