Computer Hardware and Software Questions and Answers

Answer: B

Correct answer: True

The statement is true. A dot matrix printer forms characters by striking an inked ribbon against the paper with a column of pins, so it makes physical contact - the definition of an impact printer. Its virtues follow from that contact. It can print carbon copies in one pass, which is why it survives for railway tickets, invoices and continuous stationery long after other technologies displaced it. It is also cheap to run and tolerant of poor paper. Its drawbacks are noise and low print quality. Other impact printers are the daisy wheel, line printer and drum printer. Non-impact printers make no contact and are quieter and faster: an inkjet sprays droplets of ink and gives good colour cheaply, with the cartridges rather than the printer being the real cost; a laser printer uses a laser to write a charge pattern on a drum which attracts toner, then fuses it with heat, giving fast, sharp and economical output for volume work.

Answer: A

Correct answer: ball is dirty

A mechanical mouse translates the ball's motion through two rollers, and dirt on them makes the pointer jump or stick in one axis. A driver or IRQ fault would stop the mouse working rather than make it erratic.

Answer: B

Correct answer: To draw heat away from a component and dissipate it into the air

A heat sink is a block of metal, usually aluminium or copper, cut into fins and clamped to a component. It conducts heat away from the component and presents a large surface area to the air, so the heat is carried off - usually with a fan blowing across the fins. It is needed because a modern processor dissipates tens or hundreds of watts in a few square centimetres, and silicon fails rapidly above about 100°C. Processors protect themselves by thermal throttling, reducing their clock speed as they approach the limit, and shutting down entirely if it is exceeded - so inadequate cooling shows up first as unexplained slowness rather than as failure. Thermal paste is applied between the component and the sink to fill the microscopic gaps that would otherwise trap insulating air. Larger systems use liquid cooling, circulating fluid to a radiator, where air cooling cannot remove the heat fast enough.

Answer: B

Correct answer: handshaking

Handshaking is the exchange by which two modems agree on speed, modulation, error correction and compression before any data passes - the sequence of tones heard at the start of a call.