Hardware, Memory & Number Systems
🔒 Log in to trackMemory hierarchy and units, binary/octal/decimal/hex conversions, input-output devices, ports and storage media. Number-conversion and memory-unit questions are near-guaranteed marks because they need no theory recall - only method.
One page per subtopic: detailed notes, every question type, formulas, tricks and practice sets.
Every formula on one printable page, grouped by subtopic.
5 exam-level questions worked step by step.
97 questions — untimed practice or a timed test with analysis.
Track record in the exam
Test difficulty mix (97 questions)
Question patterns exams keep repeating
Taken from previous-year papers. If a pattern is marked "very common", expect to see it in your exam.
Memory-unit ladder conversion
very common'4 GB = how many MB?', 'bits in a byte/nibble', 'which is largest: 1024 KB / 1 MB / …', or a speed question mixing megabits with megabytes.
How to solve: Convert step by step with the ×1024 ladder (bit → byte → KB → MB → GB → TB), never 1000. For speed questions, remember line speeds are in bits: divide Mbps by 8 to get megabytes per second. For 'which is largest', convert every option to one unit first.
Example: How many MB are there in 2 GB?
2 × 1024 = 2048 MB — each step up the ladder multiplies by 1024.
Binary/decimal/hex/octal conversion
very common'The decimal value of (1101)₂', 'the binary equivalent of 45', '(11011011)₂ in hexadecimal', 'how many values can 8 bits represent'.
How to solve: Base→decimal: digit × base^position from the right. Decimal→base: divide repeatedly and read remainders bottom-to-top. Binary→octal/hex: group in 3s or 4s from the right. Always verify by converting back. Digit validity is a free elimination: no 8/9 in octal, nothing after F in hex.
Example: The binary equivalent of decimal 45 is:
Divide by 2 and read remainders upward: 101101. Check: 32+8+4+1 = 45.
Volatile memory / ROM family
common'Which is volatile?', 'EPROM is erased by…', 'where is the BIOS stored?', 'SRAM vs DRAM refresh', 'cache lies where?'.
How to solve: Volatile = vanishes with power (registers, cache, RAM). Non-volatile = ROM family, flash, disk. ROM ladder: PROM once → EPROM (UV) → EEPROM (electrically) → flash. SRAM = cache (no refresh); DRAM = main memory (needs refresh); virtual memory = disk overflow, not RAM.
Example: EPROM differs from PROM because it can be erased by:
Ultraviolet light — EEPROM goes one step further and erases electrically.
Port/device identification
common'Which port carries audio + video?', 'one bit at a time', 'RJ-45 is for…', 'hot-swappable means…', 'which port for the old keyboard?'.
How to solve: Port table recall: HDMI = digital video + audio, VGA = analog video only, Ethernet/RJ-45 = network, PS/2 = old keyboard/mouse, USB = universal + hot-swap + power. Serial = 1 bit at a time over long runs; parallel = 8 bits, the old printer (LPT) port.
Example: Which port connects a computer to a wired LAN?
The Ethernet port (RJ-45) — the tabbed socket for the network cable.
Printer/device classification
common'Which is an impact printer?', 'OMR/OCR/MICR reads what?', 'plotter is used for', '3D printer produces'.
How to solve: Impact = physically strikes (dot matrix, daisy wheel); non-impact = laser, inkjet, thermal. Readers by one word: OMR marks, OCR characters, MICR magnetic ink on cheques. Plotter = large drawings; 3D printer = solid objects layer by layer.
Example: Which is an impact printer?
Dot matrix — its pins strike the ribbon against the paper; laser and inkjet never hit.
Input/output device classification
common'Which is an input device?', 'which is NOT an input device?', 'soft copy vs hard copy', 'which device is both input and output?'.
How to solve: Direction test: data flowing INTO the computer = input (keyboard, mouse, scanner, mic, readers, biometrics); results OUT = output (monitor, printer, speaker, plotter, projector). Soft copy = screen; hard copy = paper. Touch screen does both — the standard both-direction answer.
Example: A printout on paper is called a:
Hard copy — permanent output; a monitor's display is a soft copy.
Storage media identification
common'Capacity of a CD/DVD/Blu-ray', 'which storage has no moving parts', 'sequential access example', 'match medium to technology'.
How to solve: Capacity row: CD 700 MB, DVD 4.7 GB (dual 8.5), Blu-ray 25 GB with its blue-violet laser. Technology families: magnetic (HDD, tape), optical (CD/DVD/BD), flash (SSD, pen drive, card). Tape = sequential access, archival; disk/SSD = random access; SSD beats HDD on speed, loses on cost per GB.
Example: A single-layer Blu-ray disc stores about:
25 GB — its short-wavelength blue-violet laser packs far more data than a DVD's red laser.