Data Representation and Logic Basics: Revision and References
Shared revision, practice questions, answer explanations and references from the original module.
By Akhilesh Saini
Module-level quick revision
| Topic | High-yield fact | Mistake to avoid |
|---|---|---|
| Binary | Base 2; symbols 0 and 1 | Treating 10₂ as decimal 10 |
| Octal | Base 8; digits 0–7 | Allowing 8 or 9 as an octal digit |
| Decimal | Base 10; digits 0–9 | Assuming every written numeral is decimal |
| Hexadecimal | Base 16; 0–9, A–F | Forgetting A=10, F=15 |
| Binary → octal | Group 3 bits from the right | Grouping into four bits |
| Binary → hexadecimal | Group 4 bits from the right | Grouping from the left |
| Decimal → binary | Divide by 2; reverse remainders | Reading remainders top-down |
| ASCII | Standard 7-bit, 128 code values | Calling it a universal multilingual encoding |
| Unicode | Assigns code points to characters | Calling every character exactly 16 bits |
| UTF-8 | Variable-length 1–4 bytes per code point | Confusing it with a code point or encryption |
| AND | Both inputs need to be true | Treating AND like OR |
| OR | At least one input is true | Confusing OR with XOR for (1,1) |
| XOR | True when two inputs differ | Saying XOR returns 1 for (1,1) |
| NAND/NOR | Inverses; universal gates | Forgetting the inversion |
| Boolean | True/false value | Treating text "True" as always a native Boolean |
| CSV | Simple tabular text exchange | Assuming it preserves full workbook features |
| Document presentation format | Assuming a PDF is automatically authentic | |
| ZIP | File archive | Assuming every ZIP is encrypted |
| File extension | Useful filename hint | Treating it as reliable proof of contents |
Mixed review: five short prompts
- A number uses symbols
0–7. What base is it likely written in? Answer: Octal (base 8). - Write decimal 10 in binary. Answer:
1010₂(8 + 2). - Which standard assigns
U+20B9to the rupee sign? Answer: Unicode; UTF-8 is one way to encode it. - What is
1 XOR 1? Answer: 0, because XOR is true when two inputs differ. - Is a renamed
.txtfile automatically a valid.pdf? Answer: No; renaming does not change the stored format.
Sources and further reading
This module uses original explanations and original exam-style questions. Technical qualifications were checked against the following standards and educational references:
- RFC Editor — RFC 20: ASCII Format for Network Interchange — standard 7-bit ASCII code and its character representation.
- Unicode Consortium — Technical Introduction — characters, Unicode code points, and encoding forms.
- Unicode Consortium — UTF-8, UTF-16, UTF-32 FAQ — encoding lengths, UTF-8 and ASCII compatibility.
- NIST — Binary Prefixes — decimal versus binary unit terminology, linked to prior memory-units study.
- MDN — Media Types (MIME Types) — format identifiers, extensions, file signatures and handling precautions.
- MDN — Common Media Types — common documents, media and archive formats.
- MDN — JavaScript Data Types and Data Structures — examples illustrating types; exact type systems vary between software environments.