How many DMA channels are in an AT-machine?
Answer: B
Correct answer: 8
An AT class machine has two cascaded DMA controllers giving eight channels, numbered 0 to 7. Channel 4 is consumed by the cascade, leaving seven for devices - which is why the figure 7 is often quoted as well.
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In laser technology, what happens during the transfer stage?
Answer: C
Correct answer: The image is transferred from the drum to the paper
At the transfer stage the paper is given a strong positive charge, which pulls the negatively charged toner off the drum onto the page. Fusing then melts it into the fibres.
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Resistance is measured in ohm.
Answer: A
Correct answer: True
Resistance is measured in ohms, named after Georg Ohm and written with the Greek capital omega.
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You can have EISA and MCA devices in the same PC.
Answer: B
Correct answer: False
EISA and MCA are rival extensions of the PC bus, electrically and mechanically incompatible, so a machine has one or the other. EISA accepts ISA cards; MCA does not.
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The monitor power LED is 'on' but the monitor screen is completely dark. The least likely cause of the problem is:
Answer: D
Correct answer: System RAM problem
A memory fault stops the machine before it gets far, but the display would still show the POST error. The three plausible causes all lie in the video path itself - card, cable or monitor.
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What allows you to print on both sides of the printer?
Answer: B
Correct answer: duplexer
A duplex unit takes the printed sheet, turns it over and feeds it back through, so the second side can be printed without the user reinserting the paper.
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Match the device driver HIMEM.SYS to its operation.
Answer: B
Correct answer: Manages the use of extended memory
HIMEM.SYS is the extended memory manager: it arbitrates access to memory above 1 MB and provides the high memory area. EMM386 is the one that emulates expanded memory.
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Which DOS driver is used to emulate expanded memory?
Answer: B
Correct answer: EMM386.exe
EMM386 uses the 386's paging hardware to make extended memory look like expanded memory to programs that expect it. HIMEM.SYS manages extended memory itself and must be loaded first.
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Which of these is a volatile memory?
Answer: D
Correct answer: RAM
RAM is volatile: it loses its contents the instant power is removed. That is why unsaved work is lost in a power cut, and why a computer must load the operating system from disk into RAM at every start-up. The other three are non-volatile and retain data without power. ROM holds firmware written at manufacture; a hard disk stores data as magnetic patterns; a flash drive uses floating-gate transistors that hold charge indefinitely. RAM divides in two, and the difference matters. SRAM stores each bit in a flip-flop, needs no refreshing and is fast, so it is used for cache - but it takes several transistors per bit and is expensive. DRAM stores each bit as charge on a tiny capacitor which leaks and must be refreshed thousands of times a second; it is far denser and cheaper, so it is used for main memory. The name random access distinguishes both from sequential media such as tape.
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_____ help prevent power surges.
Answer: A
Correct answer: Surge suppressor
A surge suppressor clamps voltage spikes coming in on the mains before they reach the equipment. A UPS also supplies power during an outage, which is a different function.
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