CMOS Management
- Clearing CMOS via jumper/battery removal
- RTC (Real-Time Clock) drift compensation
- NVRAM corruption recovery
- Battery voltage thresholds (typically 2.7-3.3V)
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Proper procedures, communication, and safety measures in IT environments.
Learn MoreMaster the essential skills for maintaining safety, professionalism, and excellence in IT environments.
Master the art of technical translation by adapting your language to different audiences. For non-technical users, use simple analogies ("Think of RAM like a desk workspace - the bigger it is, the more projects you can have open at once"). For technical peers, be precise but concise. Always confirm understanding by asking follow-up questions like, "Does this make sense so far?" or "Would you like me to clarify any part of this?"
Effective updates follow the 4P framework:
What changed since the last update (completed work and verified outcomes).
Current blockers, incidents, or risks (include impact and who is engaged).
Next steps with ETA and validation criteria (how you will confirm success).
What you need from others (approvals, access, user actions, or decisions).
Static electricity can damage components at as little as 10-30 volts, while humans often can't feel a discharge until around 3,000 volts.
For energized electrical equipment, use a non-conductive extinguisher (typically CO2 or dry powder). In many US/Canada materials this is referred to as Class C; in the UK/EU “electrical” is usually treated as a risk category rather than a separate class—use an extinguisher rated/suitable for electrical equipment.
| Hazard | Risk | Best Practice |
|---|---|---|
| PSU capacitors | Stored charge even when unplugged | Do not open PSUs; unplug and wait before servicing a system |
| Laser printer fuser | High heat; burn risk | Allow cooldown; follow service manual handling steps |
| Lithium batteries | Puncture/thermal runaway | Replace swollen packs safely; recycle per local guidance |
| Trip/cable hazards | Injury and equipment damage | Route/secure cables; use covers and label runs |
Follow MSDS / SDS (Safety Data Sheets) for chemical handling and disposal.
Lifting: Lift with legs, keep back straight. Weight limit awareness.
Cable Management: Prevent trip hazards using velcro/ties and floor covers.
Jewelry: Remove dangling jewelry/badges when working near moving parts (fans/printers).
Protect: Customer data, passwords, and proprietary information. Privacy regulations (e.g., GDPR/UK GDPR, HIPAA) • Secure disposal • Need-to-know access
Maintain: Truthful time reporting, accurate documentation, and transparent limitations. Disclose conflicts • Reject bribes • Credit others' work
Own: Mistakes, system changes, and security incidents. Change logs • Incident reports • RCA documentation
Consider: Environmental impact, accessibility, and digital divide. E-waste recycling • Accessibility (WCAG) • Digital skills programs
Adhere to: Licensing, copyright, and regulatory requirements. Software licenses • Copyright/patents • Export controls
Ensure: Algorithmic fairness, transparency, and human oversight. Bias testing • Transparency/explainability • Human-in-the-loop
Uphold: System reliability, data backups, and disaster recovery. Reliability targets • Backup verification • DR drills
Pursue: Threat modeling, ethical hacking, and secure coding. CVE monitoring • OWASP training • Red team exercises
Always carry a professional toolkit including:
Understanding computer components, their connections, and how hardware and software work together.
Data moves through the system via buses and interfaces, with the CPU coordinating operations between components using electrical signals and binary code.
The power supply converts AC to DC power at various voltages needed by different components.
| Version | Marketing Name | Speed | Connector |
|---|---|---|---|
| USB 2.0 | High Speed | 480 Mbps | Type-A, Type-B, Mini, Micro |
| USB 3.2 Gen 1 | SuperSpeed | 5 Gbps | Type-A, Type-B, Micro-B, Type-C |
| USB 3.2 Gen 2 | SuperSpeed | 10 Gbps | Type-A, Type-C |
| USB 3.2 Gen 2x2 | SuperSpeed | 20 Gbps | Type-C Only |
| USB4 | USB4 | 20/40 Gbps | Type-C Only |
| USB4 v2 | USB4 | Up to 80 Gbps | Type-C Only |
Windows, icons, menus, and pointer (WIMP) with desktop metaphor
Hierarchical directory structure with file explorer
Built-in TCP/IP stack and network configuration tools
Disk management, task manager, and control panel
Full path from root
From current directory
Windows 11 combines GUI (windows/menus) with touch (gestures), voice access/dictation, and CLI (PowerShell/WSL) for versatile interaction.
The brain of the computer that performs calculations and executes instructions.
From vacuum tubes in the 1940s to today's nanometer-scale transistors, CPUs have evolved dramatically.
Performs all arithmetic and logical operations including:
The conductor of the CPU orchestra:
On x86, the CPU starts at the reset vector mapped to firmware (commonly physical 0xFFFFFFF0). In legacy real-mode terms this corresponds to CS:IP = F000:FFF0 (linear 0xFFFF0). The PSU Power Good signal releases reset so this first fetch can occur.
CPU executes BIOS/UEFI firmware to:
CPU loads bootloader via these steps:
CPU executes kernel startup:
When you click a browser icon:
Carries memory addresses from CPU to memory devices. Width sets a theoretical address space; real limits also depend on the memory controller, chipset/firmware mapping, and OS.
Transfers actual data between CPU and memory. Modern systems use 64-bit wide buses.
Carries signals like:
Modern CPUs can execute multiple instructions per cycle through:
Modern CPUs use deep pipelines (15-20 stages) to overlap execution:
Modern approaches to parallelism:
Check chipset support (Z790 vs B650) and BIOS requirements.
Match cooling to sustained power limits: many high-end CPUs benefit from large tower air coolers or 240mm+ AIOs for consistent boost clocks.
May require motherboard replacement if socket damaged.
Temporary storage that the CPU uses to store data that is actively being worked on.
RAM is volatile memory that provides fast temporary storage for data being actively used by the CPU.
Needs constant refreshing, used for main system memory.
Faster but more expensive, used for CPU cache.
Synchronous DRAM, first to sync with system bus
Double Data Rate, 2x transfer rate
Higher speeds, lower power
Higher bandwidth, 1.5V standard
Higher density, 1.2V standard
Higher bandwidth and density; on-die ECC (internal reliability, not the same as system ECC)
Dual In-line Memory Modules used in desktop computers and servers.
133.35mm
288 (DDR4/DDR5)
Small Outline DIMMs used in laptops and compact systems.
67.6mm
260 (DDR4), 262 (DDR5)
DDR memory is usually advertised in MT/s (mega transfers per second). The underlying clock is about half of that (MHz). A practical quick-estimate for first-word CAS latency is:
| Example | Approx. CAS latency | Takeaway |
|---|---|---|
| DDR4-3200 CL16 | ~10 ns | Balanced for many desktops |
| DDR5-6000 CL30 | ~10 ns | Higher bandwidth at similar first-word latency |
Install pairs in matching colored slots (usually 2 & 4) to double bandwidth (128-bit path).
Do not mix speeds (system slows to lowest). Do not mix ECC and Non-ECC.
Continuous beeps or specific patterns (check motherboard manual) indicate RAM failure or missing RAM.
Remove and reinstall modules. Oxidation or loose connection is a common cause of failure.
Use Windows Memory Diagnostic or MemTest86 to check for address errors.
Random BSODs, freezing, or "Page Fault" errors often point to bad RAM.
8GB
16GB
16-32GB
32GB+
Basic configuration with one RAM stick
Two identical sticks for 128-bit bus
High-end systems with four sticks
Check seating, try one stick at a time
Run memory diagnostics (Windows: mdsched.exe)
Verify running at correct speed in BIOS
ECC (Error Correcting Code) RAM uses extra bits to detect and correct memory errors (typically single-bit correction). It requires support from the CPU + motherboard. Note: DDR5 “on-die ECC” improves chip reliability but is not the same as full system ECC.
Contains a register between RAM and memory controller for stability with large amounts of RAM.
XMP (Intel) and EXPO (AMD) are one-click memory profiles. They can improve performance, but they are still overclocks relative to JEDEC defaults—if unstable, drop speed, relax timings, or use a validated kit from the motherboard QVL.
The foundational layer controlling hardware initialization, system configuration, and secure boot processes across all computing platforms.
System firmware that initializes hardware and boots the OS.
Real-time clock (RTC) plus battery-backed state. Modern systems typically store most firmware settings in UEFI NVRAM within flash; the battery mainly preserves time when power is removed.
Power-On Self-Test verifies hardware before boot.
Power On
CPU Init
RAM Test
Device Enum
Bootloader
UEFI -> Boot Manager -> Windows Boot Manager (bootmgfw.efi) or GRUB2 (Linux)
UEFI -> iPXE -> DHCP -> TFTP -> WDS/SCCM (Windows) or Cobbler (Linux)
PS/2 vs USB initialization, legacy support, NKRO (N-Key Rollover) settings
Access methods (DEL, F2, F12), navigation, hierarchy structure
Save profiles, discard changes, boot override, secure flash validation
AMI, Award, Phoenix, IBM, Dell proprietary codes
PCIe/ISA debug cards, port 80h readouts, OEM-specific LEDs
| Platform | Windows Tools | Linux Tools | macOS Tools | Enterprise Methods |
|---|---|---|---|---|
| ASUS | AI Suite, EZ Flash | fwupd (where supported), vendor utilities | N/A | ASUS Control Center |
| Supermicro | SUM (Supermicro Update Manager) | ipmitool, vendor bundles | N/A | IPMI/BMC web interface |
| Dell | Dell Command Update | fwupd, dsu | N/A | iDRAC, OpenManage |
| Apple | N/A | N/A | Software Update (firmware bundled with OS updates) | MDM-managed updates |
Chassis-level firmware vs blade-level firmware, interposer modules, management module updates
Dell OpenManage, HPE OneView, Lenovo XClarity, Cisco UCS Manager
| Vendor | Management Interface | Firmware Update Method | Unique Features |
|---|---|---|---|
| Supermicro | IPMI 2.0, Redfish | SUM, SMCIPMITool | SMBIOS/DMI customization options |
| ASUS Server | ASMB (ASUS Server Management Board) | ASUS Control Center | TPM provisioning support (platform-dependent) |
| Dell PowerEdge | iDRAC (Dell Remote Access Controller) | Dell Repository Manager | Rollback protection |
| HPE ProLiant | iLO (Integrated Lights-Out) | Service Pack for ProLiant | Silicon Root of Trust |
The foundation of every computing system - from desktops to enterprise servers
LGA, AM4/5, PGA
2-4 DIMMs
x16, x8, x4, x1
M.2, SATA
24-pin + 8-pin
1G/2.5G Ethernet
Dual/Quad Socket
8-16 DIMMs, ECC
IPMI, iDRAC
Drives, PSUs
Dual PSUs
10G/25G/40G
Connects case buttons and LEDs. Polarity matters for LEDs (+/-).
CRITICAL: Ensure standoffs match mounting holes. Extra standoffs cause short circuits.
Install before the motherboard. Watch for metal tabs grounding into ports.
If troubleshooting, test outside the case with CPU + cooler, 1 RAM stick, PSU, and (if required) GPU—then add parts back one at a time.
Comprehensive guide to AC/DC power conversion, distribution, and management for all computing environments
Main motherboard power
CPU power
GPU power
Newer high-power GPUs (use proper seating; avoid sharp cable bends)
Storage devices
Legacy peripherals
Rare legacy (floppy)
NEVER open a PSU. Capacitors hold lethal charge even when unplugged.
Devices and technologies for long-term data storage
Mass storage began with magnetic tape in the 1950s, evolving through hard disk drives (HDDs) in 1956, optical storage (CDs/DVDs) in the 1980s, and solid-state drives (SSDs) in the 2000s.
HDDs store data on spinning magnetic platters with read/write heads that move across the surface.
Stacked magnetic disks that spin at 5400-15000 RPM
Moves read/write heads across platter surfaces
512-byte or 4K segments where data is stored (Advanced Format: 512e/4Kn)
Data is arranged in concentric tracks; a cylinder is the set of tracks at the same radius across platters.
Seek time + rotational latency dominate random I/O; sequential reads/writes are much faster.
SSDs store data in NAND flash cells. A controller translates logical blocks into physical pages/blocks using a Flash Translation Layer (FTL), spreading writes to reduce wear.
Maps LBAs to flash pages, manages wear leveling, bad blocks, and error correction.
TRIM tells the SSD which blocks are no longer in use so it can clean them in the background and keep write performance steady.
Measured as TBW (total bytes written) or DWPD (drive writes per day). More writes and higher temps reduce lifespan.
| Type | Bits/cell | Common Use | Tradeoff |
|---|---|---|---|
| SLC | 1 | Enterprise/cache | Fastest/most durable, expensive |
| TLC | 3 | Mainstream SSDs | Good balance of cost, speed, endurance |
| QLC | 4 | Budget/high capacity | Lower endurance; slow sustained writes when cache fills |
Standard for 2.5" SSDs and HDDs.
Uses PCIe lanes. Direct CPU connection.
Notch positions prevent wrong install.
Older standards found in retro systems.
Splits data evenly across two or more disks.
Exact copy of data on two or more disks.
Stripes data and parity across all drives.
Like RAID 5, but stores two parity blocks so two drives can fail.
Stripe of Mirrors. Combines speed and redundancy.
Dedicated controller with processor and cache
OS-managed with CPU overhead
External enclosures with RAID support
Techniques for configuring and managing storage devices
Compatible but limited (4GB file size)
Windows standard with security features
Optimized for flash storage
Used mainly on Windows Server and some Storage Spaces scenarios. Designed for resilience against corruption and large volumes; not typically used as a boot file system on consumer Windows installs.
Built-in tool for basic partitioning
Command-line utility
EaseUS, MiniTool, AOMEI
Command-line partitioning
Graphical partition editor
Logical Volume Management
Storage Spaces lets you pool multiple drives together with resiliency options similar to RAID.
No redundancy (like RAID 0)
Data duplication (like RAID 1)
Efficiency with redundancy (like RAID 5)
Remove temporary files and system clutter
HDDs only (not needed for SSDs)
Keep TRIM enabled so the SSD can maintain performance; avoid manual defrag on SSDs.
RAID and redundancy are not backups. Verify you can restore files/systems before you need to.
Check drive health indicators
Check connections, BIOS settings, Bad Partition or Volume
Run CHKDSK (Windows) or fsck (Linux)
Check for failing sectors or SSD wear
Input and output devices that extend computer functionality with connection interfaces
Short-range wireless communication for peripherals and low-power devices (range depends heavily on obstacles and RF noise).
Practical notes: modern devices often use BLE (Bluetooth Low Energy) for better battery life; pairing creates trusted keys, so remove and re-pair if authentication gets stuck.
Universal Serial Bus (USB) versions and nominal link speeds. Names are confusing: USB-C is a connector shape, not a speed.
Real-world performance depends on the device, cable, and host controller; hubs and long/low-quality cables can cause disconnects or fall back to lower speeds.
USB-C ports may support charging (USB Power Delivery), data, and sometimes video (DisplayPort Alt Mode) or Thunderbolt.
Contactless communication technologies.
Display connection standards.
Biometric authentication using unique physical characteristics (e.g., fingerprint, face, iris).
Devices that read optical machine-readable representations of data.
Hardware devices that allow control of multiple computers from a single keyboard, video monitor, and mouse.
Graphics tablets for digital art and signatures.
Try a different port (rear I/O vs front hub), swap cable, remove hubs, and test on another system to isolate device vs host.
Replace/charge batteries, move the dongle closer (USB extension helps), reduce 2.4 GHz interference, and remove/re-pair the device.
Check default input/output device, mute/levels, app permissions, and whether it's TRRS vs separate mic/headphone jacks.
Methods and considerations for installing and upgrading operating systems.
Common ways to deliver an OS installer or image to a target machine.
Supported 64-bit CPU (1GHz+, 2+ cores), UEFI with Secure Boot support, TPM 2.0, 4GB RAM minimum (8GB+ recommended), and 64GB storage minimum (more needed for updates and feature installs).
Apple-supported Mac model; requirements vary by version (8GB+ RAM and ~20-35GB free storage is common).
Depends on distro and workload. Headless/server installs can run with less, but a modern desktop experience is typically smoother with 4GB+ RAM and ~25GB+ storage.
Managing hardware resources, file systems, and user interfaces.
System-wide search (Cmd + Space).
View all open windows and desktops.
Unix-based command line interface (zsh).
| System | OS | Features |
|---|---|---|
| NTFS | Windows | Permissions, journaling, compression, large files. |
| FAT32 | All | Max 4GB file size. High compatibility. |
| exFAT | All | No 4GB limit. Optimized for flash drives. |
| ext4 | Linux | Journaling, high performance. |
| APFS | macOS | Optimized for SSDs, encryption. |
Firmware initializes hardware.
Power-On Self-Test checks RAM, CPU, Video.
Locates OS kernel (Windows Boot Manager / GRUB).
OS core loads into memory and starts services.
Navigating and configuring operating system settings and features.
Monitor and manage running processes (Windows).
Monitor system resources (macOS).
Linux equivalent for process management.
Managing user accounts, groups, and access control in operating systems.
Common account types in Windows. In practice you’ll also see local accounts, Microsoft accounts, and domain identities (Active Directory / Entra ID joined).
Key idea: use least privilege—work as a standard user and elevate only when needed (UAC prompt).
Unix-like systems separate identity (users/groups) from capability (permissions). Root is powerful; prefer sudo with logging.
Windows uses ACLs (Access Control Lists) with Allow/Deny entries that can be inherited. Effective access is the combination of: NTFS permissions (on the file/folder) and, if accessed over the network, share permissions (the most restrictive wins).
Classic Unix permissions are rwx for owner / group / others. Extras you must know: setuid, setgid, and the sticky bit (common on shared temp dirs).
Centralized configuration and security enforcement for Windows in AD domains. Useful for password/lockout policy, software deployment, firewall rules, drive mappings, and hardening. Remember LSDOU: Local → Site → Domain → OU (later policies can override earlier ones).
Techniques for keeping operating systems running smoothly and efficiently.
Regular tasks to keep the OS stable, secure, and performant.
Control what launches at boot/login to reduce boot time and background CPU/RAM usage.
Disable or reconfigure services only when you understand dependencies. Prefer changing startup apps first; record changes so you can revert.
Swap/pagefile is a stability feature. If RAM is tight, the system will page—watch for high disk activity and sustained hard faults.
| Symptom | Likely Causes | First Checks |
|---|---|---|
| Slow boot | Startup apps, updates, disk issues | Startup list, update status, disk health |
| High CPU | Runaway process, malware, updates | Per-process CPU, AV scan, update activity |
| High disk usage | Paging, indexing, failing drive | RAM pressure, disk queue, SMART/NVMe health |
Automating tasks and managing systems remotely.
Windows command scripting for simple automation.
@echo off
echo Hello World
pause
Object-based automation (Windows and cross-platform).
Write-Host "Hello"
Get-Service | Where-Object Status -eq 'Running'
Linux/macOS shell scripting (common on servers).
#!/bin/bash
echo "Hello World"
ls -la
Remote GUI access (commonly secured with NLA/TLS).
Encrypted command-line access (Linux/macOS/Windows).
Secure file transfer over SSH (preferred over FTP).
Unencrypted command-line access (Insecure!).
Platform-independent graphical desktop sharing.
Remote management for Windows (use HTTPS where possible; commonly used in enterprise automation).
Diagnosing and resolving common operating system issues.
Check BIOS boot order. Ensure drive is detected.
Bootloader/BCD corruption. Use Startup Repair, or WinRE tools like `bootrec /fixmbr`, `bootrec /rebuildbcd`, or `bcdboot` (common on UEFI systems).
Check Event Viewer (System Log). Boot into Safe Mode.
Preventive (stop), Detective (identify), and Corrective (recover) controls work together.
Understanding monitor types, connectors, and troubleshooting.
| Name | Resolution | Notes |
|---|---|---|
| 1080p | 1920x1080 | Common baseline |
| 1440p | 2560x1440 | Sharper, more GPU load |
| 4K | 3840x2160 | Great for text; scaling often used |
Fast response times (often 1-5ms). Weaker viewing angles and color accuracy.
Strong color accuracy and viewing angles. Response times range widely; check reviews for motion handling (GtG, overshoot) if gaming matters.
Best contrast (deep blacks). Compromise between TN and IPS.
Organic Light Emitting Diode: No backlight. Each pixel emits its own light.
The fundamental backbone of modern communication: Models, Protocols, and Addressing.
Format: Dotted Decimal
192.168.1.1
~4.3 billion addresses (limited; public allocation largely exhausted)
Format: Hexadecimal
2001:0db8:85a3:0000:0000:8a2e:0370:7334
~3.4e38 addresses (vast address space)
CIDR notation (/24, /16, and similar prefixes) tells you how many bits are the network prefix. The rest are host bits.
| CIDR | Mask | Hosts (IPv4) | Typical Use |
|---|---|---|---|
| /24 | 255.255.255.0 | 254 | Small LAN / VLAN |
| /16 | 255.255.0.0 | 65,534 | Large site (often split into smaller VLANs) |
| /30 | 255.255.255.252 | 2 | Point-to-point links |
IPv4 host count is typically 2^(32 - prefix) - 2 (network + broadcast reserved) in traditional subnets.
| Port | Protocol | Use Case | Transport |
|---|---|---|---|
| 20/21 | FTP | File Transfer Protocol (Unsecured) | TCP |
| 22 | SSH | Secure Shell (Remote Login) | TCP |
| 23 | Telnet | Remote Terminal (Unsecured) | TCP |
| 25 | SMTP | Simple Mail Transfer (Sending) | TCP |
| 53 | DNS | Domain Name System | UDP/TCP |
| 67/68 | DHCP | Dynamic Host Config | UDP |
| 80 | HTTP | Web Traffic (Unsecured) | TCP |
| 110 | POP3 | Post Office Protocol (Receiving) | TCP |
| 143 | IMAP | Internet Message Access (Receiving) | TCP |
| 443 | HTTPS | Secure Web Traffic (TLS) | TCP |
| 3389 | RDP | Remote Desktop Protocol | TCP/UDP |
Technologies and devices for connecting computers in a limited area.
Internet
│
Modem / ONT
│
Router (NAT + DHCP + Firewall)
│
Switch ────────────────┐
│ │
Access Point Wired Clients
(Wi‑Fi) (PCs/Printers/NAS)
| Cat | Speed | Max Dist |
|---|---|---|
| Cat 5e | 1 Gbps | 100m |
| Cat 6 | Up to 10 Gbps | Up to ~55m (10GBASE-T) |
| Cat 6a | 10 Gbps | 100m |
| Cat 8 | Up to 40 Gbps | Up to ~30m |
Most common wiring standard (RJ45).
Wi-Fi standards, security, and configuration for wireless networks.
| Standard | Freq (GHz) | Max Speed | Notes |
|---|---|---|---|
| 802.11a | 5 | 54 Mbps | Legacy. Short range. |
| 802.11b | 2.4 | 11 Mbps | Legacy. Long range. |
| 802.11g | 2.4 | 54 Mbps | Backwards compatible with 'b'. |
| 802.11n (Wi-Fi 4) | 2.4 / 5 | 600 Mbps | Introduced MIMO (Multiple Antennas). |
| 802.11ac (Wi-Fi 5) | 5 | ~7 Gbps | MU-MIMO (Multi-User). Beamforming. |
| 802.11ax (Wi-Fi 6) | 2.4 / 5 (6 for Wi-Fi 6E) | ~9.6 Gbps | OFDMA (Efficiency). High density. |
| 802.11be (Wi-Fi 7) | 2.4 / 5 / 6 | ~46 Gbps | Multi-Link Operation (MLO). Very high throughput/low latency. |
Note: “Max Speed” values are theoretical PHY rates. Real throughput depends on channel width, client capability, distance/interference, AP load, and encryption overhead.
Longer range, better wall penetration, but crowded.
Faster speeds, more channels (availability depends on regulatory domain and DFS rules), less interference than 2.4 GHz, shorter range.
Connection types, Cloud Computing, and DNS.
| Type | Medium | Characteristics | Speed |
|---|---|---|---|
| Fiber | Light (Glass) | Fastest, Low latency, Immune to EMI. | 1 Gbps+ (often multi-gig) |
| Cable | Coaxial (Copper) | Shared bandwidth with neighbors. TV lines. | ~100 Mbps-1+ Gbps |
| DSL | Telephone (Copper) | Dedicated line. Speed drops with distance. | Up to ~100 Mbps |
| Satellite | Radio Waves | Latency depends on orbit: GEO is high; modern LEO constellations can be much lower. Line of sight and weather effects still apply. | Varies (often tens to hundreds of Mbps) |
| Cellular | 4G / 5G | Mobile. Tethering/Hotspot capabilities. | Varies (signal, congestion, plan, device) |
Domain Name System translates names to IP addresses.
Records have a TTL (cache time). “DNS propagation” is usually just caches expiring + replicas updating.
The technology that abstracts hardware to run multiple operating systems and services.
Installs directly on the server hardware without a host OS. Used in enterprise data centers for maximum performance.
Runs as an application on top of an existing operating system. Ideal for testing, development, and end-user sandboxing.
End-user applications delivered over the web. No maintenance required by the user.
Tools and environment for developers to build and deploy apps without managing infrastructure.
Virtual hardware (servers, storage, networks) that you manage and configure yourself.
Snapshots save the state of a VM at a point in time (useful for testing updates). They depend on the base disk. If the base disk fails, the snapshot is lost.
Backups are independent copies of the data stored separately. They are required for disaster recovery.
In cloud services, the provider secures the underlying infrastructure (datacenters, physical hosts). You are typically responsible for identity/access, data, configuration, and patching what you control (especially in IaaS).
VM connects directly to the physical network. It gets its own IP address from the physical router/DHCP server.
VM shares the host's IP address. The host acts as a router for the VM. VM can access the internet, but outside devices can't see the VM easily.
VM connects only to the host and other VMs on the same private network. No internet access.
Must support virtualization extensions (Intel VT-x or AMD-V) and be enabled in BIOS/UEFI.
Sufficient memory for the host OS plus all running VMs. (e.g., 16GB+ recommended).
Fast storage (NVMe SSD) is critical for VM performance. Large capacity for virtual disk files.
Virtual switches plus NAT/bridged/host-only networking for VM connectivity and isolation.
Hardware, displays, and power management for laptops and mobile workstations.
Often a power-tuned CPU (sometimes a full SoC) designed around heat and battery limits. Performance can vary with power profiles and sustained load.
Small Outline Dual In-line Memory Module. Roughly half the size of desktop DIMMs.
Many thin laptops use soldered low-power RAM (LPDDR). Faster and efficient, but typically not upgradeable.
Modern laptops commonly use M.2 NVMe SSDs. Older models may use 2.5" SATA SSDs/HDDs.
Mini-PCIe or M.2 Key E cards for Wi-Fi and Bluetooth connectivity.
Heat pipes/vapor chamber, fans, and thermal paste/pads. Dust buildup and dried paste can cause throttling and unexpected shutdowns.
Typically Li-ion/LiPo packs with a battery management controller. Charging may be vendor-specific or USB-C Power Delivery depending on the model.
TN/IPS/VA or OLED. Most modern laptops use eDP; older models may use LVDS. Backlight issues often appear as a very dim image under a flashlight.
The glass overlay that converts touch inputs into digital signals (for touchscreens).
Display cables flex through the hinge area. Intermittent flicker or backlight loss can be caused by a damaged eDP/LVDS cable.
Integrated into the top bezel. Privacy shutters are becoming common.
Proprietary or USB-C/Thunderbolt. Provides power, display outputs, and extra ports. Capability depends on the laptop port (USB-C with DP Alt Mode vs Thunderbolt/USB4) and the dock.
Adds extra ports (often via USB). May not supply charging power or support multiple high-resolution displays like a full dock.
USB-C to HDMI/DP adapters rely on DisplayPort Alt Mode support. If video does not work, confirm the port supports video, try a different cable, and avoid low-quality adapters.
Some laptops support external GPUs over Thunderbolt/USB4. Useful for graphics workloads; performance depends on the link and GPU enclosure.
Kensington Lock slots for physical security in public spaces.
Tip: Swollen batteries are a fire hazard. Dispose of them properly immediately.
Smartphones, tablets, and the ecosystems that power them.
Protecting mobile devices, data, and users from modern threats.
Gaining elevated/admin access. Weakens platform protections and increases malware risk. May break warranty/support and security updates.
Removing Apple's restrictions. Allows unauthorized apps but exposes system to malware.
Malicious SMS/IM messages and QR codes that trick users into installing apps, handing over credentials, or approving MFA prompts.
Installing apps outside official stores. Increases the risk of malware and unsafe permissions.
Overly broad access (SMS, Accessibility, device admin, contacts) can enable data theft, overlays, or persistent control.
Attackers transfer your number to a new SIM to intercept calls/SMS. Use authenticator apps, SIM PIN, and carrier port-out protections.
Third-party markets often lack rigorous security checks.
Greater risk of Man-in-the-Middle (MitM) attacks on untrusted networks; prefer VPN and HTTPS/TLS.
Avoid unknown USB ports/cables. Use your own charger or a charge-only adapter; keep USB data access locked when possible.
Technologies, maintenance, and troubleshooting for modern printing devices.
Uses liquid ink. Thermal (bubble) or Piezoelectric (vibration) nozzles. High quality photos, slower speed.
Heat transfers dye to photo paper in layers (typically CMY + overcoat). Common for photo kiosks; great gradients and photo consistency.
Heat-sensitive paper (Direct Thermal) or ribbon (Thermal Transfer). Used for receipts and labels.
Pins strike a ribbon. Noisy but useful for multi-part carbon forms.
Inkjet head alignment and color calibration; for lasers, configuration pages and color registration help maintain consistent output.
Run cleaning cycles for inkjet heads; clean rollers and remove dust. Use a toner-safe vacuum only (household vacuums can spread fine toner).
Toner/ink, imaging drum (sometimes separate), fuser (laser), transfer belt/roller, pickup rollers and separation pads, and periodic maintenance kits.
| Protocol | Typical Port(s) | Notes |
|---|---|---|
| IPP | 631 | Modern printing; common for “driverless” setups. |
| IPPS | 443 / 631 | IPP over TLS (encrypted). Port depends on implementation. |
| RAW (JetDirect) | 9100 | Simple TCP stream; very common on network printers. |
| LPD/LPR | 515 | Legacy line printer protocol. |
| SMB | 445 | Printing via a print server share; permissions matter. |
| mDNS / Bonjour | 5353 (UDP) | Local discovery; often blocked across VLANs or guest isolation. |
Common page description languages include PCL, PostScript, and PDF direct. A wrong driver can cause gibberish prints or missing features.
Identifying threats and implementing physical and logical security controls.
Encrypts data and demands payment for the key.
Malware disguised as legitimate software.
Records keystrokes and user activity silently.
Embeds deep in OS to hide itself and other malware.
A virus typically attaches to files and needs user action; a worm self-propagates over networks without user interaction.
A group of compromised devices controlled remotely, often used for DDoS attacks and spam.
Controls are often categorized by Type (how they are implemented) and Function (what they do).
| Type | Examples | Primary Function |
|---|---|---|
| Technical (Logical) | Firewalls, Antivirus, Encryption, ACLs, MFA | Prevent/Detect via software/hardware |
| Administrative (Management) | Policies, Training, Background Checks, Risk Assessments | Govern behavior and processes |
| Physical | Locks, Fences, Guards, Lighting, Mantraps | Restrict physical access |
Best practices for safety, documentation, and professional conduct.
Strong RFCs include: scope, risk, test plan, rollback/backout, comms plan, maintenance window, and a clear success/verification step.
Use antistatic wrist straps and mats, and connect them to a proper ground to prevent static discharge.
Use an electrical-rated extinguisher (commonly CO2 or dry powder). Never use water on energized equipment.
Safety Data Sheets for handling chemicals (toner, cleaners).
Maintain manufacturer-recommended temperature and moderate humidity (often ~40-60%) to reduce ESD and corrosion risk.
Uninterruptible Power Supply for outages; Surge protector for spikes.
Identify the issue, report to proper channels, and protect evidence (do not turn off if volatile data is needed).
Document exactly who handled evidence, when, and where to maintain legal integrity.
Curated collection of resources to enhance your computer science journey.