ICT in Libraries I: Character Representation (ASCII, ISCII, Unicode), Hardware, Storage and Input-Output Devices; System and Application Software; Programming and Web Languages; Telecommunication; and Wireless Communication
2. Computer hardware, storage devices and input-output devices
Hardware is the physical equipment of a computer. The central processing unit contains the arithmetic logic unit, the control unit and registers; primary memory is RAM (volatile working memory), ROM (permanent start-up instructions) and cache. Storage is measured in bytes of 8 bits, with 1 KB = 1,024 bytes in the binary convention and MB, GB, TB and PB each 1,024 times the last. Storage devices are magnetic (hard disks, tapes still used for backup and archives), optical (CD about 700 MB, single-layer DVD 4.7 GB, single-layer Blu-ray 25 GB), solid-state (SSDs, USB flash drives, memory cards) and networked or cloud storage.
| Input devices | Output devices |
|---|---|
| Keyboard, mouse, touch screen | Monitor and projector |
| Scanners (flatbed, overhead book scanners) with OCR software | Printers: impact (dot-matrix) and non-impact (laser, inkjet, thermal for receipts and labels) |
| Barcode readers, RFID readers, smart card readers, biometric scanners | 3D printers in makerspaces; Braille embossers for print-disabled users |
| OMR (optical mark reading), MICR (magnetic ink character recognition), webcams and microphones | Speakers and headphones, including screen-reader audio |
3. Types of software; programming languages
System software runs the computer and supports other programs: operating systems (Windows, Linux, macOS, Android), utilities (antivirus, backup, compression), device drivers and language translators (compilers translate a whole program before running it, interpreters translate and run line by line, assemblers translate assembly language). Application software does users' tasks: general-purpose packages (word processors, spreadsheets, database management systems, presentation software) and special-purpose packages, among them library management software such as Koha, SOUL, e-Granthalaya and commercial systems. By licence, software is proprietary (closed source, licensed for a fee), free and open source (source code available, with freedom to use, study, modify and share, under licences such as the GNU GPL), freeware (free of charge but closed) or shareware (try before paying).
| Language type | Features | Examples |
|---|---|---|
| Machine and assembly (first and second generation) | Binary instructions or mnemonic codes tied to one processor | Processor instruction sets |
| High-level procedural (third generation) | Programs as sequences of procedures and functions acting on data; portable across machines | FORTRAN, COBOL, C, Pascal |
| Object-oriented | Programs built from objects that combine data and methods; classes, encapsulation, inheritance and polymorphism | C++, Java (DSpace is written in Java), Python, C# |
| Scripting | Interpreted, quick to write, used to automate tasks and build web applications | Perl (Koha is written in Perl), PHP, JavaScript, Python, shell scripts |
| Fourth and fifth generation | Declarative: say what is wanted, not how; logic programming for AI | SQL for databases; Prolog |
| Web languages | Markup for structure, style sheets for presentation, scripts for behaviour | HTML (now a living standard maintained by WHATWG), CSS, XML (W3C, 1998) and JavaScript |
4. Telecommunication: channels, modes, media, ISDN, PSDN, multiplexing, modulation and standards
A transmission channel carries signals from sender to receiver. By direction, transmission modes are simplex (one way only, as in broadcast radio), half-duplex (both ways but one at a time, as in a walkie-talkie) and full-duplex (both ways at once, as in a telephone call); data can also be sent serially (bit after bit) or in parallel, and synchronously or asynchronously. Transmission media are guided (twisted-pair copper, coaxial cable and optical fibre, which carries light, offers the highest bandwidth and is immune to electrical interference) or unguided (radio, microwave, infrared and satellite links). Bandwidth, the capacity of a channel, is measured in bits per second.
| Term | Meaning |
|---|---|
| ISDN (Integrated Services Digital Network) | Digital transmission of voice and data over telephone lines; the basic rate interface is 2B + D, two 64 kbps bearer channels and one 16 kbps signalling channel, 144 kbps in all; the primary rate interface is 23B + D (1.544 Mbps) or 30B + D (2.048 Mbps) |
| PSDN | Usually expanded as packet switched data network (also called a public switched data network): a public data network, typically based on the X.25 protocol, that breaks data into packets routed independently |
| PSTN (Public Switched Telephone Network) | The circuit-switched telephone network, over which early libraries connected by dial-up modems |
| Multiplexing | Sharing one channel among several signals: frequency division (FDM), time division (TDM), wavelength division (WDM, on optical fibre) and code division (CDM) |
| Modulation | Varying a carrier wave to carry information: amplitude, frequency or phase modulation (AM, FM, PM), and for digital data ASK, FSK, PSK and QAM; a modem (modulator-demodulator) converts between digital data and analogue signals |
| Standards bodies | ITU-T (telecommunication), ISO (including the OSI reference model), IEEE (LAN and wireless standards such as 802.3 and 802.11), IETF (internet protocols) |
5. Wireless communication: media, Wi-Fi, Li-Fi, satellite and mobile communication
| Technology | Key facts | Library use |
|---|---|---|
| Wi-Fi | Wireless LAN under the IEEE 802.11 family, in the 2.4, 5 and 6 GHz bands; recent generations are Wi-Fi 6 (802.11ax) and Wi-Fi 7 (802.11be) | Campus-wide access to e-resources and the OPAC on users' own devices |
| Li-Fi (Light Fidelity) | Data carried by rapidly modulated visible or infrared light from LEDs; demonstrated by Harald Haas (2011) and standardised by IEEE as 802.11bb; confined to the lit room, so hard to intercept, and free of radio interference | Possible in reading rooms and sensitive areas where radio signals are unwanted |
| Bluetooth and NFC | Short-range personal networks (Bluetooth, IEEE 802.15.1) and near-field communication at centimetres (13.56 MHz, as used by library RFID) | Beacons for location-based alerts; mobile check-out |
| Satellite communication | Geostationary satellites orbit about 35,786 km above the equator once every 24 hours, appearing fixed; low-earth-orbit constellations give lower delay; India's INSAT and GSAT series | Distance education and connectivity for remote libraries |
| Mobile communication | 1G analogue voice; 2G digital (GSM, CDMA) with SMS; 3G mobile data; 4G LTE all-IP broadband; 5G with very high speed and low latency (launched in India in October 2022) | Mobile OPACs, apps and SMS alerts (Unit IV) |
Key takeaways
- ASCII (1963) is 7-bit with 128 codes; ISCII (IS 13194:1991) is 8-bit with Indian scripts in the upper half; Unicode (1991) has 1,114,112 code points in 17 planes, Devanagari at U+0900 to U+097F, encoded as UTF-8, UTF-16 or UTF-32.
- Hardware: CPU, RAM, ROM, cache; storage is magnetic, optical (CD 700 MB, DVD 4.7 GB, Blu-ray 25 GB), solid-state or cloud; library input devices include barcode, RFID and smart card readers and book scanners.
- System software (OS, utilities, drivers, compilers and interpreters) runs the machine; application software (including Koha, SOUL, e-Granthalaya) does tasks; languages are procedural (C), object-oriented (Java, used by DSpace), scripting (Perl, used by Koha) and web (HTML, CSS, XML, JavaScript).
- Modes are simplex, half-duplex and full-duplex; media guided (twisted pair, coaxial, optical fibre) or unguided; ISDN basic rate 2B + D = 144 kbps; PSDN is a packet-switched data network, PSTN the circuit-switched telephone network; multiplexing FDM, TDM, WDM; modulation AM, FM, PM, ASK, FSK, PSK, QAM.
- Wireless: Wi-Fi (IEEE 802.11), Li-Fi (visible light, 802.11bb), Bluetooth and NFC, geostationary satellites at about 35,786 km, and mobile generations from 1G to 5G (India, October 2022).
Practice questions (10)
Attempt each one before opening the answer. Every explanation names the tempting wrong option as well as the right one, because that is where marks are lost.
Standard ASCII uses 7 bits per character. How many distinct characters can it encode? Type the number.
Numerical answer — type the value.
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Answer: 128
Seven bits give 2⁷ = 128 combinations, codes 0 to 127, covering English letters, digits, punctuation and control characters. Eight-bit extensions double this to 256.An ISDN basic rate interface has two 64 kbps B channels and one 16 kbps D channel. What is its total capacity in kbps? Type the number.
Numerical answer — type the value.
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Answer: 144
2B + D = 2 × 64 + 16 = 128 + 16 = 144 kbps. The two B channels carry voice or data and the D channel carries signalling.Which Indian standard code places Indian scripts in the upper half of an 8-bit code table, with ASCII in the lower half?
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Answer: D — ISCII
ISCII, adopted as IS 13194:1991, keeps ASCII in codes 0 to 127 and uses 128 to 255 for Indian scripts. EBCDIC is IBM's mainframe code, UTF-32 a fixed-width Unicode encoding, and Baudot an old telegraph code.A walkie-talkie, in which both parties can transmit but only one at a time, uses which mode of transmission?
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Answer: B — Half-duplex
Half-duplex allows two-way communication but not simultaneously. Simplex is one way only (broadcast radio), full-duplex is both ways at once (a telephone call), and multiplexing is sharing one channel among signals, not a direction mode.Which of the following are system software? Select all that apply.
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Answer: A — A compiler; C — An operating system such as Linux
Operating systems and language translators such as compilers are system software. Koha and spreadsheets perform users' tasks, so they are application software.Assertion (A): Optical fibre is preferred for high-capacity campus network backbones. Reason (R): Optical fibre is a guided transmission medium. Choose the correct option.
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Answer: B — Both A and R are true, but R is not the correct explanation of A
Both are true, but R does not explain A. Twisted pair and coaxial cable are guided media too, so being guided cannot be why fibre is preferred; the reason is its very high bandwidth, low signal loss over long distances and immunity to electromagnetic interference.Li-Fi transmits data using:
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Answer: C — Modulated visible or infrared light from LEDs
Li-Fi modulates light from LEDs faster than the eye can see, and the IEEE has standardised it as 802.11bb. Wi-Fi uses radio in the 2.4, 5 and 6 GHz bands; twisted pair and satellites are other media.Which statements about Unicode are correct? Select all that apply.
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Answer: B — The Devanagari block is U+0900 to U+097F; C — Its code space runs from U+0000 to U+10FFFF; D — UTF-8 encodes English text identically to ASCII
Unicode's range is U+0000 to U+10FFFF, UTF-8 is ASCII-compatible for English, and Devanagari sits at U+0900 to U+097F. Characters take one to four bytes in UTF-8, so the last statement is false.Koha, the open source integrated library system, is written mainly in:
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Answer: A — Perl
Koha is written in Perl with a MySQL or MariaDB database, and DSpace is written in Java. COBOL is a business language, FORTRAN a scientific one, and Prolog a logic language for AI.Which multiplexing technique is used to send many signals over a single optical fibre on different wavelengths of light?
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Answer: D — Wavelength division multiplexing
WDM sends each signal on its own wavelength (colour) of light through the same fibre. TDM gives each signal a time slot, CDM separates signals by codes, and amplitude modulation is a way of carrying one signal, not of sharing a channel.