Sonali & Janata Bank Ltd. Officer (IT) Exam: 2020প্রশ্ন ও সমাধান

Correct answer: (b) Student

An entity is a real-world thing with an independent existence about which the database keeps data: a person, a product, a course or, here, a student. In an ER diagram it is drawn as a rectangle and it normally becomes a table. Entities are the nouns of the model. Attributes are the properties that describe an entity; they are drawn as ovals and become columns.

Why the other options are wrong

• (a) Roll No.: A property of a Student (usually its key attribute), so it is an attribute, not an entity.
• (c) Passport No.: A property of a person (it could serve as a candidate key), so it is an attribute.
• (d) Department ID: The identifying attribute of a Department entity, or a foreign key column in Student. The ID itself is an attribute; the entity would be Department.

Tip: Entity = a noun that gets its own table (Student, Department); attribute = a fact about it (Roll No., Department ID).

Source: CSCI 403 Lecture 9: Relational Database Design and Entity-Relationship Diagrams (Colorado School of Mines)

Correct answer: (a) Uses electromagnetic signal

RFID (Radio-Frequency Identification) is made of a reader and a tag. The reader sends a radio-frequency signal, the tag's antenna picks it up (a passive tag is even powered by this energy), and the tag answers with its stored ID. Radio waves are electromagnetic waves, so RFID works by electromagnetic signals in LF, HF, UHF or microwave bands. Because radio passes through many materials, RFID does not need a clear line of sight, unlike a barcode.

Why the other options are wrong

• (b) Uses laser beam: Laser beams are used by barcode scanners, which need line of sight to the printed code; RFID uses radio instead.
• (c) Uses optical signal: Optical (visible-light) links belong to barcode readers, cameras and optical fibre, not to RFID tags.
• (d) Uses infrared: Infrared is used by TV remotes and IrDA links, which need line of sight; RFID works in radio bands.

Tip: RFID = Radio-Frequency IDentification: tag + reader talking by radio (electromagnetic) waves, no line of sight needed.

Source: RF Subsystem - Glossary, NIST CSRC; NIST Issues Guidelines for Ensuring RFID Security - NIST

Correct answer: (a) ROM

The bootstrap program must be available the instant power is applied, before anything has been loaded. It is therefore kept in non-volatile firmware memory on the motherboard: traditionally ROM, and on modern PCs a rewritable flash ROM that holds the BIOS/UEFI. NIST's BIOS protection guideline describes BIOS firmware as stored in the system flash memory. This firmware runs the POST and then starts the next-stage loader from the boot disk.

Why the other options are wrong

• (b) Hard disk: holds the OS and the later-stage loaders that the firmware reads in; the very first program has to run before the disk has even been initialised.
• (c) CD: removable boot media; a CD can carry a loader, but the computer still needs the ROM firmware to read it.
• (d) RAM: volatile; it is empty at power-on, so it cannot store the bootstrap program.

Exam note: Booting has stages. The first-stage bootstrap sits in ROM (today, flash memory, an electrically rewritable kind of ROM) and loads further loader code from disk (for example the master boot record). Exam questions mean the first stage, so "ROM" is the answer.

Tip: First code at power-on = ROM/flash firmware; OS = disk → RAM.

Source: NIST SP 800-147, BIOS Protection Guidelines; Windows startup issues troubleshooting (Microsoft Learn)

Correct answer: (c) FORTRAN

FORTRAN (FORmula TRANslation) was developed at IBM by a team led by John Backus and released commercially in 1957 for the IBM 704. It let scientists and engineers write mathematical formulas instead of machine instructions, came with the first optimizing compiler, and became the first computer language standard. It is therefore regarded as the first (widely used) high-level programming language. Earlier experimental systems such as A-0 and Autocode existed, but none achieved FORTRAN's adoption.

Why the other options are wrong

• (a) C: Created by Dennis Ritchie in 1972, fifteen years after FORTRAN.
• (b) COBOL: Its design began in 1959, for business data processing, two years after FORTRAN.
• (d) C++: It was built as an extension of C, so it came after C and long after FORTRAN.

Tip: FORTRAN (1957) = first high-level language, for science and engineering; COBOL (1959) = for business.

Sources: Fortran | IBM; Fortran - Wikipedia; COBOL - Wikipedia; C (programming language) - Wikipedia

Correct answer: (b) light

A barcode reader shines light from its own light source (an LED, or a laser in some readers) onto the code. Black bars have low reflectance and white spaces high reflectance, so the reflected light changes across the code. A photosensor (a photodiode or a line image sensor such as a CCD) turns the reflected light into an electrical signal, which is amplified, converted to binary and decoded into the stored data. So the reader emits light, and reading depends on how that light is reflected.

Why the other options are wrong

• (a) sound: No sound is used to read the code; the reading is entirely optical.
• (c) beeps: A beep is a sound signal, not the light that reads the code; the reading itself is entirely optical.
• (d) smell: Has nothing to do with scanning.

Tip: Barcode reader = light source + sensor + decoder; black bars reflect little light, white spaces reflect a lot.

Source: EP 0610504 A1, Information reading apparatus (bar code reader) — European Patent Office; Barcode reader — Wikipedia