Hardware, Memory & Number Systems
🔒 Log in to trackPorts and connectors
🔒 Log in to trackA port is an interface on the cabinet for connecting peripherals.
| Port | Purpose / notes |
|---|---|
| Serial (COM/RS-232) | Sends one bit at a time; suits slow data over long distances; old modems/mice |
| Parallel (LPT, 25-pin) | Sends 8 bits (a byte) at once; traditional printer port; short distance |
| PS/2 | 6-pin round; keyboard (purple) & mouse (green); legacy |
| USB | Universal Serial Bus; hot-swappable, power + data. USB 2.0 = 480 Mbps, USB 3.x = 5-20 Gbps; Type-A/B/C |
| VGA (DB-15) | 15-pin, analog video only to monitors/projectors |
| DVI | Digital video (older digital standard) |
| HDMI | Digital audio + video in one cable; TVs/monitors |
| DisplayPort | Digital audio + video, daisy-chaining; PCs |
| Thunderbolt | Combines DisplayPort + PCIe over USB-C; very high speed |
| Ethernet (RJ-45) | Wired LAN |
| Audio jacks (3.5 mm) | Green = line-out/speakers, Pink = mic, Blue = line-in |
| Game port / FireWire (IEEE 1394) | Legacy joystick; high-speed media, superseded by USB |
Hot-swappable = connect/disconnect while the PC runs (USB, FireWire) - serial/parallel ports are not.
What a port is
A port is a socket on the cabinet where a cable or device plugs in. Each port has a job — carry video, connect a network, take a keyboard — and exams ask "which port for which job?".
Serial vs parallel — the classic comparison
| Serial port | Parallel port | |
|---|---|---|
| Bits per transfer | One bit at a time | A whole byte (8 bits) at once |
| Wires | Few | Many |
| Distance | Long distances, less interference | Short distances |
| Classic use | Old modems, mice (COM port) | Old printers (LPT port) |
Memory hook: Serial = Single lane; Parallel = multi-lane highway.
The port table
| Port | Job |
|---|---|
| USB (Universal Serial Bus) | Everything today — pen drives, keyboards, phones. Hot-swappable and supplies power (5 V) |
| HDMI | Digital video + audio in one cable — monitor, TV, projector |
| VGA | Analog video only (15-pin, blue) — older monitors; no sound |
| DisplayPort | Digital video + audio, common on PCs and monitors |
| Ethernet (RJ-45) | Wired network/LAN connection |
| PS/2 | Round 6-pin — old keyboard and mouse |
| Audio jack (3.5 mm) | Speakers, headphones, mic (green = out, pink = mic) |
| Serial (COM/RS-232) | One-bit-at-a-time legacy data link |
| Parallel (LPT) | Legacy 25-pin printer port |
USB facts exams like
- Hot-swappable — connect or remove while the computer runs, no restart.
- USB supplies power, so pen drives and small keyboards need no adapter.
- Speeds grew by generation: USB 2.0 ≈ 480 Mbps, USB 3.0 ≈ 5 Gbps.
- USB Type-C — the small reversible oval plug now common on phones and laptops.
How exam questions sound
| Stem words | Answer |
|---|---|
| 'Picture and sound, one digital cable' | HDMI |
| 'Old blue connector, video only' | VGA |
| 'One bit at a time' | Serial (COM) |
| 'Printer port of old machines' | Parallel (LPT) |
| 'Network cable socket' | Ethernet / RJ-45 |
| 'Round purple and green sockets' | PS/2 keyboard and mouse |
| 'Plug in without restarting' | USB (hot-swap) |
| 'Speakers, green round hole' | 3.5 mm audio jack |
A 10-second method
- Underline the JOB in the stem (video? sound? network? data direction?).
- Match the job to the table row — ports are defined by what they carry.
- If two options look close, drop the one whose extra capability the stem excludes (VGA fails any 'audio' stem; parallel fails any 'long distance' stem).
Question types you will see
Each type: how to recognise it, the method step by step, and one question to try.
Serial vs parallel comparison
'How many bits does a parallel port send?', 'which port sends one bit at a time?', 'which port was used for printers (LPT)?', statement pairs on wires and distance.
Serial = 1 bit at a time, few wires, long distance. Parallel = 8 bits (a byte) at once, short distance, old printer port (LPT).
'One bit at a time' always means serial — even if USB is also serial inside.
Statement versions plant a reversal (serial = 8 bits) — check each number.
A parallel port transfers how much data per transfer?
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A full byte (8 bits) at once — eight wires side by side. A serial port moves the same byte as 8 single bits in sequence.
Port identification by purpose
'Which port connects to a network?', 'video + audio in one digital cable', 'the round port for an old keyboard', 'green socket for speakers'.
Network = Ethernet/RJ-45; digital AV = HDMI/DisplayPort; analog video only = VGA; old keyboard/mouse = PS/2; speakers/headphones = 3.5 mm audio jack.
'Single cable, picture and sound, digital' = HDMI in exam language.
USB is the universal fallback — if no specific job matches, USB fits.
Which port connects a computer to a wired LAN/network?
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The Ethernet port (RJ-45) — the wide tabbed socket that takes the network cable.
USB facts (hot-swap, power, versions)
'Hot-swappable means…', 'why does a pen drive work without its own power?', 'USB 3.0 is faster than 2.0 because…'.
Hot-swappable = plug/unplug while the PC is running, no restart.
USB carries power (5 V) along with data — that is why pen drives need no adapter.
Version speeds: USB 2.0 ≈ 480 Mbps, USB 3.0 ≈ 5 Gbps (about 10× faster).
USB is called hot-swappable because —
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You can connect or remove a USB device while the computer is running — no shutdown or restart needed.
Display and audio ports
'Which port carries only video?', 'VGA vs HDMI', 'which port for speakers?', statements about analog/digital video.
VGA = analog, video only, 15 pins. HDMI and DisplayPort = digital, video + audio.
The green 3.5 mm socket = line-out for speakers; pink = microphone.
'No sound from my VGA monitor cable' is the everyday proof of the exam line.
Which port carries analog video only, with no audio?
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VGA — the 15-pin blue connector of older monitors. HDMI and DisplayPort carry both video and audio in digital form.
Shortcuts that save time
Serial sends a Single stream (1 bit at a time, slow, long distance); Parallel sends a Packet (whole byte across 8 wires, fast, short distance - old printers).
Which port transmits one bit at a time?
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Serial port.
VGA = Video only (15 pins, analog); HDMI = Home-theatre cable: audio + video, digital. If the question says 'sound and picture together' -> HDMI.
Which port carries digital audio and video?
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HDMI.
Mistakes to avoid
Where most students lose marks on this subtopic.
Calling VGA capable of audio - VGA is video-only.
Saying serial ports are faster than parallel - parallel moves a byte per transfer (over short runs).
Forgetting USB is hot-swappable - that phrase in the question usually points to USB.
Quick revision
Read this the night before the exam.
Serial = 1 bit at a time, long distance; parallel = 8 bits (a byte), printers (LPT).
HDMI = digital audio + video; VGA = analog video only, no audio.
Ethernet/RJ-45 = network; PS/2 = old keyboard/mouse; 3.5 mm = audio.
USB = hot-swappable + supplies power; USB 2.0 ≈ 480 Mbps, USB 3.0 ≈ 5 Gbps.
Practice: 15 questions
Sets of 10, mixed across the question types above. Every answer has a step-by-step explanation.
Topic test · 10 questions
Suggested time 4 min · wrong answers go to your mistake notebook automatically.