Computer Fundamentals, Hardware and Software

Chapter 3 · General IT · 3 questions in the paper · 16 min read

Computer Fundamentals, Hardware and Software

What the syllabus asks for 3
  • Generations, types and parts of a computer
  • Input, output and storage devices, memory
  • System and application software, operating systems, number systems

General IT carries about five of the ten GK-and-IT questions: three on computer fundamentals (this chapter) and two on the Internet, HTML, programming and full forms (the next).

The Dean's Office model asked "which is not an output device" (OCR), SSD/storage, and the father of the computer. Everything here is stable knowledge; learn the tables.

What the paper asks from this chapter
  • Generations: vacuum tube → transistor → IC → microprocessor → AI.
  • Devices: which are input, output, storage.
  • Memory: RAM is volatile, ROM is not; units (byte, KB, MB, GB).
  • Software: system vs application; operating systems.
  • Number systems: binary, octal, hexadecimal conversions.

3.1 Generations, types and parts of a computer

Generation Technology
First (1940–56) vacuum tubes (ENIAC)
Second (1956–63) transistors
Third (1964–71) integrated circuits
Fourth (1971– ) microprocessors
Fifth artificial intelligence

Types by size: supercomputer, mainframe, minicomputer, microcomputer (PC, laptop). The CPU has the ALU (Arithmetic Logic Unit), the control unit and registers; it is called the brain of the computer. Charles Babbage is the "father of the computer".

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(a) 1st: vacuum tube
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(b) 2nd: transistor
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(c) 3rd: integrated circuits
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(d) 4th: microprocessor
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(e) 5th: AI hardware
Plate 3.1. Real hardware of the five generations, left to right: (a) a vacuum tube (first), (b) a power transistor (second), (c) integrated circuits in DIP packages (third), (d) a modern microprocessor (fourth), (e) a Google TPU AI accelerator board (fifth).Photo credits: (a) 池田正樹 masaki ikeda, Public domain; (b) Mister rf, CC BY-SA 4.0; (c) Kimmo Palosaari, Public domain; (d) Eric Gaba, CC BY-SA 4.0; (e) Zinskauf, CC BY-SA 4.0.

diagram
Figure 3.1. The five generations drawn to scale on one time axis. The first three generations last 16, 7 and 7 years; the fourth has lasted more than 55 years because the microprocessor is still the heart of every PC and phone. Fifth-generation work (AI) overlaps the fourth, so exam papers treat it as artificial intelligence rather than a single hardware date.

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(a) Charles Babbage (1791-1871)
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(b) Difference Engine (built 1991 from his plans)
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(c) IBM 1401: Nepal's first computer
Plate 3.2. Charles Babbage, called the father of the computer, and his machines: (a) Babbage; (b) a working Difference Engine built from his plans; (c) an IBM 1401, the machine that arrived in Nepal for the 2028 BS census.Photo credits: (a) anonymous, Public domain; (b) Frankie Roberto from Manchester, UK, CC BY 2.0; (c) Marcin Wichary, CC BY 2.0.

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(a) Supercomputer racks
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(b) IBM mainframe (System z)
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(c) PDP-11 minicomputer
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(d) Laptop: microcomputer
Plate 3.3. Computers by size, largest to smallest: (a) a supercomputer (Cray XE6 racks), (b) an IBM mainframe, (c) a DEC PDP-11 minicomputer, (d) a laptop (microcomputer).Photo credits: (a) Derrick Coetzee from Berkeley, CA, USA, CC0; (b) Agiorgio, CC BY-SA 4.0; (c) Don DeBold, CC BY 2.0; (d) André Karwath aka Aka, CC BY-SA 4.0.

diagram
Figure 3.2. Types of computers by size and power. The triangle narrows towards the top: only a few supercomputers exist, while billions of microcomputers (PCs, laptops, phones) are in use. Speed and price rise upwards; numbers fall.

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(a) Motherboard with numbered parts
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(b) Intel 8086 die: the CPU on a chip
1CPU socket2RAM slots3PCIe slot4Chipset524-pin power
Plate 3.4. The parts of a computer, from the real board: (a) a micro-ATX motherboard with its main parts numbered; (b) the die of an Intel 8086 microprocessor, with the ALU, control unit and registers all on one chip.Photo credits: (a) Jacek Halicki, CC BY-SA 4.0; (b) Pdesousa359, CC BY-SA 3.0.

diagram
Figure 3.3. Block diagram of a computer. The CPU contains the ALU (arithmetic and logic), the control unit and registers. Instructions and data come from main memory (RAM) over the buses, input devices feed data in, output devices take results out and secondary storage keeps files permanently.

3.2 Input, output and storage devices, memory

Input Output Storage
keyboard, mouse, scanner, microphone, light pen, joystick monitor, printer, plotter, speaker, projector HDD, SSD, pen drive, CD/DVD, memory card
OCR, OMR, MICR, barcode reader
  • OMR reads pencil marks (answer sheets); OCR reads printed text; MICR reads magnetic ink on bank cheques. All three are input devices.
  • RAM is volatile main memory; ROM is non-volatile; cache is the fastest and sits near the CPU; SSD/HDD are secondary (mass) storage.
  • 1 byte = 8 bits; 1 KB = 1,024 bytes; 1 MB = 1,024 KB; 1 GB = 1,024 MB.

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(a) OMR sheet: pencil marks
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(b) Cheque with MICR line
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(c) Barcode scanner
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(d) Joystick
Plate 3.5. Special input devices that GK papers ask about: (a) an OMR mark sheet read by light, (b) a cheque with the MICR line of magnetic-ink digits at the bottom, (c) a handheld barcode scanner, (d) a joystick.Photo credits: (a) The Japan Racing Association, Public domain; (b) SRI International, CC BY-SA 3.0; (c) Network.nt, Public domain; (d) Bultro, CC BY-SA 4.0.

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(a) Trackball
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(b) USB microphone
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(c) Flatbed scanner
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(d) Light pen on SAGE console
Plate 3.6. More input devices: (a) a trackball, (b) a USB microphone, (c) an open flatbed scanner, (d) a light pen and console from the SAGE air-defence system.Photo credits: (a) Bobulous, CC BY-SA 4.0; (b) Nicolas Rück, CC BY-SA 3.0; (c) Bultro, CC BY-SA 4.0; (d) Tomwsulcer, CC0.

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(a) Monitor 1920x1080
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(b) Video projector
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(c) Plotter
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(d) Inkjet printer inside
Plate 3.7. Output devices: (a) a monitor showing a 1920 x 1080 test pattern, (b) a video projector, (c) a pen plotter for large technical drawings, (d) an inkjet printer with its cover removed.Photo credits: (a) Lucasbosch, CC BY-SA 4.0; (b) Dave Pape, Public domain; (c) Windell Oskay, CC BY 2.0; (d) Klosito, CC BY-SA 3.0.

diagram
Figure 3.4. Classification of devices. Note the red box: OCR, OMR, MICR and barcode readers are all input devices, a favourite trick question, because they read data into the computer even though their names sound like machines that print.

diagram
Figure 3.5. Memory hierarchy: speed and cost per byte fall, and capacity rises, going down. The typical times are rounded: a hard disk access (about 10 ms) is 100,000 times slower than a RAM access (about 100 ns). Registers, cache and RAM are volatile; ROM, SSD and HDD keep data when the power is off.

diagram
Figure 3.6. The storage-unit ladder: each step is x 1,024 (2 to the power 10), not x 1,000. All the values are computed. A pen drive sold as 4 GB holds 4 x 1,024 = 4,096 MB; 1 byte = 8 bits.

3.3 System and application software, operating systems, number systems

  • System software: operating system (Windows, Linux, macOS, Android), device drivers, utilities, language translators. Application software: MS Word, Excel, browsers, games.
  • An OS manages processes, memory, files and devices. It does not "design web pages".
  • Translators: compiler (whole program), interpreter (line by line), assembler (assembly to machine code).
  • Number systems: binary (base 2), octal (8), decimal (10), hexadecimal (16, digits 0–9 and A–F). Examples: (1010)_2=10, (13)_{10}=(1101)_2, (17)_8=15, (FF)_{16}=255, A_{16}=10. Four bits make 16 values.

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(a) SRAM chip (cache type)
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(b) DRAM module (RAM)
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(c) SD memory card
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(d) USB pen drive
Plate 3.8. The storage family in real life: (a) static RAM chip, the type used for cache; (b) a DDR4 DRAM module, main memory; (c) an SD memory card; (d) a USB pen drive.Photo credits: (a) Satyamfifa, Public domain; (b) ElooKoN, CC BY-SA 4.0; (c) Mister rf, CC BY-SA 4.0; (d) Dmitry Makeev, CC BY-SA 4.0.

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(a) HDD: platter and read-write arm
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(b) DVD (optical, laser)
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(c) NVMe SSD (flash)
Plate 3.9. Secondary storage up close: (a) a hard disk platter and head arm, (b) a DVD, (c) an NVMe SSD. The disk spins and has moving parts, the DVD is read by a laser, and the SSD has no moving parts at all.Photo credits: (a) Mk2010, CC BY 4.0; (b) Unknown author, Public domain; (c) D-Kuru, CC BY-SA 4.0.

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(a) MS-DOS
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(b) Windows 10
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(c) Ubuntu Linux
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(d) Android
Plate 3.10. Operating systems you must recognise: (a) MS-DOS, a command-line OS; (b) Windows 10; (c) Ubuntu Linux; (d) Android, the most widely used mobile OS.Photo credits: (a) Ghettoblaster, Public domain; (b) Fatemi, CC BY-SA 4.0; (c) Rprpr, CC BY 3.0; (d) Pikalab, CC0.

diagram
Figure 3.7. Software classification. System software runs the machine (operating system, drivers, utilities, translators); application software does the user's job (word processor, spreadsheet, browser, games). An OS does not design web pages; a browser does not manage memory.

diagram
Figure 3.8. Translators. A compiler reads the whole program and writes an executable file (C, C++); an interpreter reads one line, runs it, then reads the next (Python, JavaScript); an assembler turns assembly mnemonics into machine code. Only the compiler gives a separate output file.

diagram
Figure 3.9. Number-system conversion worked on (214) in decimal. Repeated division by 2 (remainders read bottom to top) gives 11010110; grouping bits in fours gives hexadecimal D6; grouping in threes gives octal 326. All values are computed and checked: 3 x 64 + 2 x 8 + 6 = 214 and 13 x 16 + 6 = 214.

3.4 Eight traps in computer-fundamentals questions

Computer questions look easy, which is why marks leak. These eight traps are drawn from the Dean's Office model (OCR as the odd one out, SSD, the father of the computer) and from past TU entrance papers.

  1. OCR, OMR and MICR are input devices. They read marks, text or magnetic ink into the computer, so a question "which is not an output device" can have OCR as the correct answer (Fig 3.4). A bank cheque with a MICR line, an exam sheet read by OMR and a barcode at a Bhat-Bhateni till are three Nepali examples. A printer or a plotter, by contrast, only sends results out.
  2. Volatile means data is lost at power-off. RAM, cache and registers are volatile, while ROM, SSD, HDD and pen drives keep their data. If the stem asks for "the fastest memory" the answer is cache or registers, not RAM. If it asks for "main memory" the answer is RAM.
  3. SSD is storage, not main memory. A solid-state drive uses flash chips but acts as secondary storage, like a hard disk, only much faster because it has no spinning parts (Plate 3.9). Do not choose SSD for "primary memory" or "volatile memory". Remember the order: register, cache, RAM, SSD, HDD.
  4. 1 KB is 1,024 bytes. The ladder uses powers of 2, so 1 MB = 1,024 KB and 1 GB = 1,024 MB (Fig 3.6). A shop may sell a 500 GB disk using 1 GB = 1,000,000,000 bytes, but the exam key uses 1,024. Convert carefully: 2 GB = 2 x 1,024 = 2,048 MB, and 1 byte is always 8 bits.
  5. Match the generation to the technology. First generation is the vacuum tube (ENIAC), second the transistor (IBM 1401, which Nepal used for the 2028 BS census), third the integrated circuit, fourth the microprocessor, and fifth artificial intelligence. A question that says "microprocessor" is the fourth generation even if the machine is a laptop in your hand. Associate each generation with its photograph in Plate 3.1 and you will not mix them up.
  6. System software versus application software. The operating system, device drivers, utilities and translators are system software; Word, Excel, a browser and a game are application software (Fig 3.7). Windows and Android are operating systems, so they are system software even though you use them every day. An OS manages processes, memory, files and devices, but it does not design web pages.
  7. Compiler or interpreter? A compiler translates the whole program at once and produces an executable file, so it is used for C and C++. An interpreter works line by line and stops at the first error, which is how Python and JavaScript normally run. An assembler is the third translator and it converts assembly language, not high-level code (Fig 3.8).
  8. Number-system digits and base. Binary uses 0 and 1, octal 0-7, decimal 0-9 and hexadecimal 0-9 plus A-F, where A is 10 and F is 15. So (FF)16 = 15 x 16 + 15 = 255, and four bits make 16 values (0 to 15). If a digit is larger than the base allows, such as 8 in an octal number, the option is wrong.

3.4.1 Worked checks

Q. Convert (101111) in binary to hexadecimal and decimal.

Answer. Group from the right in fours: 0010 1111, which is 2 and F, so the hexadecimal number is 2F. In decimal, 2F = 2 x 16 + 15 = 47, and checking directly, 32 + 8 + 4 + 2 + 1 = 47.

If the options include 2F and 47 together, both are consistent. Fig 3.9 shows the same method on the number 214.

Q. Which of the following is not an output device? (a) Plotter (b) Projector (c) OCR (d) Speaker

Answer: (c). A plotter draws large diagrams, a projector throws the screen on a wall and a speaker produces sound, so all three send information out of the computer.

OCR (optical character recognition) reads printed text and sends it into the computer, so it is an input device. The key idea is the direction of the data: into the CPU is input, out of the CPU is output.

Formula and fact sheet

Item Fact
Vacuum tube / transistor / IC / microprocessor 1st / 2nd / 3rd / 4th
Volatile memory RAM, cache
1 byte 8 bits
(FF)_{16} 255

Chapter summary

  • OCR, OMR, MICR and barcode readers are input devices.
  • RAM loses its data when power is off; ROM does not.
  • SSD and HDD are storage, not main memory.
  • A compiler translates all at once; an interpreter line by line.
  • Fourth generation = microprocessor.

Practice questions

Set A — Recall (20 questions)

  1. Which generation of computers used vacuum tubes?afourthbthirdcseconddfirst
  2. Second-generation computers usedavacuum tubesbtransistorscintegrated circuitsdmicroprocessors
  3. The brain of the computer is theaCPUbmonitorcRAMdkeyboard
  4. Which of these is NOT an output device?aplotterbmonitorcOCRdprinter
  5. RAM isanon-volatilebvolatilecread-onlydpermanent
  6. ROM isalost when power is offbfreely writablecvolatilednon-volatile
  7. One byte equals how many bits?a4b6c8d16
  8. One kilobyte equals how many bytes?a1,024b1,000c512d8
  9. Which of these is an input device?aprinterbmonitorcspeakerdscanner
  10. An SSD is a type ofacache memorybsecondary (mass) storagecRAMdregister
  11. Which is an operating system?aMS WordbChromecLinuxdExcel
  12. Which is application software?aMS ExcelbWindowscLinuxdBIOS
  13. Which is the fastest among these?ahard diskbcache memorycDVDdUSB drive
  14. ALU stands foraArray Logic UnitbApplied Logic UnitcAdvanced Logical UnitdArithmetic Logic Unit
  15. The binary form of decimal 5 isa101b110c111d100
  16. The decimal value of (1010)_2 isa8b12c10d5
  17. Charles Babbage is known as theainventor of the Internetbfather of the computercinventor of the mousedcreator of Windows
  18. BIOS stands foraBinary Input Output SoftwarebBasic Integrated Output SystemcBasic Input Output SoftwaredBasic Input Output System
  19. Fourth-generation computers useavacuum tubesbtransistorscmicroprocessorsdartificial intelligence
  20. A laptop is aamicrocomputerbmainframecsupercomputerdminicomputer
Answers and explanations — Set A

1. (d) — first generation, 1940–56.

2. (b) — transistors replaced vacuum tubes.

3. (a) — the CPU processes all instructions.

4. (c) — OCR reads text into the computer: an input device.

5. (b) — RAM loses its contents without power.

6. (d) — ROM keeps its contents.

7. (c) — 8 bits.

8. (a) — 1 KB = 2¹⁰ = 1,024 bytes.

9. (d) — a scanner sends data in.

10. (b) — solid-state drives store data permanently.

11. (c) — Linux; the others are applications.

12. (a) — Excel is an application program.

13. (b) — cache is faster than disks.

14. (d) — Arithmetic Logic Unit.

15. (a) — 4 + 1 = 101.

16. (c) — 8 + 2 = 10.

17. (b) — he designed the Analytical Engine.

18. (d) — Basic Input Output System.

19. (c) — the microprocessor era.

20. (a) — personal computers are microcomputers.

Set B — Understanding (12 questions)

  1. One megabyte equalsa1,000 KBb1,024 KBc512 KBd1,024 bytes
  2. The decimal value of (FF)_{16} isa16b15c256d255
  3. The binary form of decimal 13 isa1101b1011c1110d1001
  4. The decimal value of (17)_8 isa17b14c15d16
  5. The part of the CPU that fetches and decodes instructions is theaALUbcontrol unitcRAMdROM
  6. Which is NOT a function of an operating system?amemory managementbfile managementcprocess managementddesigning web pages
  7. The device that reads pencil marks on answer sheets isaOMRbOCRcMICRdbarcode reader
  8. MICR is mainly used inaschoolsbhospitalscbanksdcinemas
  9. A compileratranslates one line at a timebtranslates the whole program at oncecremoves commentsdrepairs hardware
  10. The translator that converts assembly language into machine code is theacompilerbinterpreterclinkerdassembler
  11. Which memory is volatile?aROMbHDDcRAMdSSD
  12. The binary form of decimal 10 isa1010b1001c1100d1111
Answers and explanations — Set B

1. (b) — 1,024 KB.

2. (d) — 15 × 16 + 15 = 255.

3. (a) — 8 + 4 + 1.

4. (c) — 1 × 8 + 7 = 15.

5. (b) — the control unit.

6. (d) — web design is done with application tools.

7. (a) — optical mark recognition.

8. (c) — cheque processing.

9. (b) — an interpreter works line by line.

10. (d) — assembler.

11. (c) — RAM loses data when power is off.

12. (a) — 8 + 2.

Set C — Application (8 questions)

  1. The binary sum 101 + 11 equalsa1000b1001c110d1010
  2. The number of bits needed to represent 16 distinct values isa3b8c4d16
  3. One gigabyte equalsa1,000 MBb1,024 MBc100 MBd512 MB
  4. The decimal value of the hexadecimal digit A isa11b9c12d10
  5. The largest value in one byte isa127b128c255d256
  6. The integrated circuit was introduced in theathird generationbfirst generationcsecond generationdfourth generation
  7. The first general-purpose electronic digital computer wasaMark IbAltaircApple IdENIAC
  8. The CPU consists ofaRAM and ROM onlybALU, control unit and registerscmonitor and keyboarddprinter and scanner
Answers and explanations — Set C

1. (a) — 5 + 3 = 8 = 1000.

2. (c) — 2⁴ = 16.

3. (b) — 1,024 MB.

4. (d) — A is 10 in hexadecimal.

5. (c) — 11111111 = 255.

6. (a) — third generation (1964–71).

7. (d) — ENIAC (1945).

8. (b) — ALU, control unit and registers.