Computer Fundamentals Questions and Answers

Answer: A

Correct answer: SVC

An SVC - supervisor call - is the routine the processor transfers control to when an interrupt occurs: the current instruction stream is suspended, the machine switches to supervisor state and enters that handler, which services the condition and then returns. IP is the instruction pointer and MDR the memory data register - both registers, not sections of code.

Answer: D

Correct answer: Control unit

The control unit fetches each instruction from memory, decodes it to work out what is required, and then issues the timing and control signals that make the other units carry it out. The logic unit performs the arithmetic and comparisons it is told to, storage holds data, and input merely delivers it.

Answer: A

Correct answer: 2

The binary system has two digits, 0 and 1, so its base - its radix - is 2, and each place is worth twice the one to its right: \( 1011_2 = 1\times2^3 + 0\times2^2 + 1\times2^1 + 1\times2^0 = 11 \). Base 8 is octal, base 10 decimal and base 16 hexadecimal.

Answer: C

Correct answer: Assembler

An assembler translates assembly language - mnemonic instructions such as MOV and ADD - into the machine code the processor executes, mostly one instruction for one instruction. A compiler translates a high-level language, and an interpreter executes a high-level program statement by statement without producing a machine-code file.

Answer: B

Correct answer: CPU cycle

The complete fetch–decode–execute sequence for one simple machine instruction is a CPU cycle (also called the machine or instruction cycle). Seek time is how long a disk arm takes to reach a track, and real time refers to processing that must keep pace with external events.

Answer: B

Correct answer: Effective time

Effective time is the portion of the scheduled time during which a piece of equipment is actually operating and doing useful work - as against the idle and down time that make up the rest. Access and seek times measure how quickly storage responds, not how long the machine runs.

Answer: C

Correct answer: Binary base is small

With only two digits available, each binary place carries a factor of 2, whereas a decimal place carries a factor of 10. A number therefore needs about \( \log_2 10 \approx 3.32 \) times as many binary places as decimal ones - the decimal 1000 takes four digits but \( 1111101000_2 \) takes ten. The small base, not the size of the numbers, is the reason.

Answer: B

Correct answer: Sequential

Tape is a long strip that can only be wound past the head from one end towards the other, so reaching a particular record means passing over everything recorded before it - sequential access. Direct and random access require a medium whose parts can be reached in any order, such as a disk.

Answer: C

Correct answer: Intermediate storage

Storage used to hold partial results between one step of processing and the next is intermediate storage. It is a role rather than a place: the same primary or internal storage serves as intermediate storage when it is holding a value that is neither the original input nor the final output.

Answer: C

Correct answer: HMOS

HMOS - High-performance Metal Oxide Semiconductor - was Intel’s name for the scaled-down NMOS process it introduced in the 1970s, giving faster switching and greater density; the 8085 and 8086 were built with it. HDLC, LAP and SDLC are data-link communication protocols.