Hardware & Communication Foundations – Full Study Notes

Clear, shared terminology is critical in both human and computer communication.
- One term can carry different personal meanings; always verify the universal definition.
- In networking, the “language” = protocol; mis-understanding a protocol term can break a whole configuration.
Practical study tactic: create a master term list for quizzes; cross-out terms as you match them to definitions.

Desktop ATX power supplies provide three main DC “rails”:
- $3.3\text{\ V}$ (orange wires)
- $5\text{\ V}$ (red wires)
- $12\text{\ V}$ (yellow wires)
Connector types & where they go
- $20\text{-pin}$ or $24\text{-pin}$ : main motherboard connector (always present)
- $4\text{-pin}$ or $8\text{-pin}\,12\text{ V}$ EPS: supplemental CPU power
- VGA/PCIe auxiliary: $6\text{-pin}$ or $8\text{-pin}$ for GPUs
- Legacy Molex → SATA adapters exist when older PSUs must power newer drives.
Wattage sizing: add up component draws (CPU, GPU, drives, fans) and buy a PSU that comfortably exceeds the total.

AT vs. ATX
- AT (obsolete): instant-off power switch, no 5-second hold.
- ATX (standard today): soft power, requires 4–5 s hold to hard-off.
Board sizes
- ATX > Micro-ATX > Mini-ITX. Smaller = fewer PCIe slots, sometimes lower VRM capacity.
All-in-One PCs = laptop hardware bolted behind a monitor; niche uses (kiosk, kitchen calendar, touch panel).

“BIOS” historically; modern firmware is UEFI (often labelled “UEFI BIOS”).
- Stores board configuration in NVRAM (CMOS region powered by a $\text{CR2032}$ coin cell).
- POST (Power-On Self-Test) checks: CPU, RAM, chipset, video, minimal storage presence.
- Secure Boot & BitLocker require UEFI + GPT partition tables.
- Virtualisation flags (Intel VT-x / AMD-V) toggled here; must be ON for Hyper-V, VMware, etc.
POST diagnostics when no speaker present:
- LED debug panel on some boards
- PCI/PCIe POST cards (display hex codes) map to failure charts in the manual.

DIMM = Dual-Inline Memory Module (gold fingers on both sides; reads/writes simultaneously).
- SODIMM = laptop/printer size.
- SIMM (Single-Inline) = pre-DIMM, only one side active.
Channeling
- Dual, triple, quad channel modes double/triple/quad effective bandwidth. Populate matching-colour slots.
DDR generations
- DDR3 supports up to triple channel; DDR4/5 support quad.

SATA vs. eSATA vs. SATA-e
- eSATA: external port form for hot-swap drives.
- SATA-e: “SATA Express,” higher bandwidth combo of SATA & PCIe (rare in consumer gear).
Optical drives (DVD/BD) mostly gone; keep a USB external burner for legacy install media.

Legacy → modern order: VGA (DB-15) → DVI → DisplayPort → HDMI → USB-C (Alt-Mode, power + data + video).
Docking station vs. port replicator
- Dock: proprietary connector; turns laptop into desktop (multiple displays, power).
- Port replicator/HUB: USB-C/USB-A; generic extra ports.

PS/2 (purple = keyboard, green = mouse) — not hot-swappable; avoid when possible.
Serial DB-9 (COM) & DB-25 (parallel/printer) mostly in servers/industrial.
USB-to-RJ45 dongle: quick NIC add for laptops without Ethernet.

Every device needs a unique MAC & IP address.
Loopback address (IPv4): $127.0.0.1$ — use ping 127.0.0.1 to test local TCP/IP stack.
Key CLI tools (Windows syntax shown):
- ping – reachability; add -t for continuous.
- ipconfig /all – view NIC config.
- tracert – hop-by-hop path.
- netstat -an – open sockets & listening ports.
Physical cable test tools
- Toner & probe (fox & hound): inject tone at wall jack, locate in patch-panel bundle.
- Cable testers: verify $1!\rightarrow!8$ pinout, detect shorts or cross-over.

Wear antistatic wrist strap or touch chassis ground regularly; avoid wool, carpet shuffling.
Remove power, hold power button $\approx10\text{ s}$ ("power-purge") to drain residual charge.
CRT monitors & PSU capacitors store lethal voltages; treat as black-box, discharge before service.
Keep dropped screws out of cases—shorts through motherboard back can kill components.

Precision Phillips & flat screwdrivers
Torx set, nut drivers
Tweezers & hemostats (retrieve dropped screws)
Cable crimper, stripper, scissors
Spare SATA, Molex->SATA power, PCIe power cables
USB flash drive toolkit (drivers, firmware, malware scanner, WinPE)
Multimeter for detailed voltage troubleshooting; power-supply tester for quick rail check.

$24\text{-pin}$ ATX ‑ main board power
$4\text{ / }8\text{-pin}$ EPS-12 V ‑ CPU power
$6\text{ / }8\text{-pin}$ PCIe ‑ GPU power
SATA data (7-pin L-shaped) vs. SATA power (15-pin)
RJ-45 = Ethernet; RJ-11 = phone.
ZIF (Zero Insertion Force) ribbon locks in laptops: flip-up/slide latch, no pulling force.

If motherboard under warranty → replace, don’t re-solder tiny VRMs.
Out-of-warranty but mission-critical legacy gear (door controllers, industrial PLC): component-level repair may be justified.
Evaluate labour-time vs. risk; sometimes junk the board and buy new.

Bluetooth logo = Nordic runes of King Harald “Bluetooth” Gormsson; range $\approx10\text{ m}$ , not 40 yd.
Analog vs. digital in gaming: console thumbstick (analog) vs. mouse (digital, faster).
Pentium Pro “cartridge” CPU & vertical Slot 1 heatsinks demonstrated as historic form factors.
Netbooks/Chromebooks: low-power packet-sniffers or closet diagnostics machines.
Zip / ESATA / Thunderbolt — know port shapes from textbook pictures for ID on certification exam.

Vocabulary quiz: definitions shown, choose term from drop-down; bring your own term-only list.
Correct expansion-card removal: pull straight out (front-to-back), never rock side-to-side—prevents bent “fingers.”
POST code LEDs/beeps vary by vendor—download manual whenever you face unfamiliar board.