What device prevents power interruptions, resulting in corrupted data?
Answer: A
Correct answer: Battery back-up unit
Only a UPS keeps the machine running through a power interruption, so that work in memory is written out and the system shut down properly. A surge protector guards against excess voltage but supplies nothing when the mains fails.
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What device protects against line deficiencies?
Answer: B
Correct answer: UPS
Line deficiencies are shortfalls - sags, brownouts and outages - and only a UPS supplies power to make them up. A surge protector deals with the opposite problem, excess voltage.
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COM 4 uses which I/O port?
Answer: D
Correct answer: 2E8H
The standard serial addresses are COM1 at 3F8, COM2 at 2F8, COM3 at 3E8 and COM4 at 2E8.
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A dot matrix printer is an example of an impact printer.
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.
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The mouse pointer moves erratically, what is the possible cause? The mouse
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.
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What is the purpose of a heat sink in a computer?
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.
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_____ is the term used to refer to the process of two modems establishing communications with each other.
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.
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