The Visible Computer—CompTIA A+ (220-1001) A-PLUS Certification Prep Course Notes

The Visible Computer

A computer gets work or play done. A computer will have a CPU, RAM, mass storage, & an OS.

Primary PC Components
- System unit, Monitor (output), Keyboard & mouse (input), Printer (paper output); Speakers, game controllers, web cameras, external hard drives, headsets, microphones.

External Connections
- USB, network cable connections (RJ45); DVI; HDMI; older: mini-din (PS2); Parallel port; serial port; VGA.

What is a computer?
- What is an Operating System?
  - A program that runs the other programs (the conductor).
    - An OS controls all the programs on a computer.
  - Kernel—the core part of the OS that handles the primary memory management. The core of the operating system is the kernel.
  - PID—process identification; every program running gets its own PID (Running programs are called processes)
  - OS deals with hardware
    - Devices drivers are needed by the OS; OS’s use device drivers to ‘talk’ to hardware.
    - Drivers are programs that act as the interface between hardware & the OS (device drivers “talk” to the hardware)
    - Storage
    - Networking
- Users & Super Users
  - All OSes have user accounts with encoded passwords.
  - All operating systems have super user accounts that have complete access to everything!!!
  - The Windows super-user is called the “Administrator”. (i.e.–the ‘admin’ account)
  - The Linux & macOS super-user is called “Root”.

Why Windows?
- Microsoft invented the concept of per-processor agreements.
- Every Windows system has its own local usernames & passwords.
- Windows Active Directory domains store domain usernames & passwords.
- Single sign-on enables users to log in using their domain accounts anywhere on the network.
- Both OS x and Linux use Windows networking for single sign-on

Windows Editions & Versions
- Be comfortable with the different editions of Windows.
- Recognize which editions can join a domain.
- Understand the basics differences between Windows 7, 8, 8.1, and 10.

Touring the masOS
- Be familiar with different versions of macOS, including the current version.
- Recognize the main parts of the masOS desktop.
- Make sure you can manipulate application windows and dialog boxes.
- Understand the functions of Finder, System Preferences and the Terminal.

Touring Linux (Ubuntu)
- Linux is freeware under the GNU license.
- Linux is commonly packaged in distributions (distros).
- Fedora, Mint, & Ubuntu are three popular distros.

CPU
- Central Processing Unit are the chips used to run programs
- Every CPU has an internal feature to process commands
- Every CPU runs code based on a specific machine language
- CPU use pipelines to optimize the processing commands
- CPU is the ‘brain’ of the machine, the calculator performing many calculations per second. Like a “man in a box”.
- CPUs have a clock speed, commonly measured in GHz (billions cycles/sec)
- CPUs come in primarily two makes: Intel & AMD
- CPUs take a system speed & multiply it to reach the CPU speed
- Single CPUs often have multiple cores

Cache
- CPU caching works between RAM and the CPU
- CPU is built into the CPU
- Its common to have 3 cache’s in a CPU—L1, L2, & L3. (Level 1, Level 2, Level 3)
- Study “set association” on YouTube

Microprocessors/CPUs
- 32-bit and 64-bit processing
- CPUs come in 32-bit and 64-bit versions
- 32-bit CPUs cannot address more than 4 Gigabytes of memory
- Operating Systems come in both 32 & 64-bit versions
- Most 64-bit processors also run into 32 bit mode

CPU Sockets
- Microarchitecture—in essence, the circuit diagram on the inside of the CPU
- CPU sockets are the mount where a CPU connects to the motherboard.
- Many different CPUs come from a single microarchitecture (ex: Intel i3, i5, i7, i9)
- There are specific CPU socket packages covered on the A+ exam

Installing a CPU
- Building your own computer starts with choosing a CPU & a motherboard. They have to work with one another, i.e.—be compatible. For example, an Intel CPU will need the right Intel motherboard, & an AMD CPU will need an AMD motherboard.
- Make sure you have the right socket and speed CPU for your motherboard.
- Always use thermal paste between the CPU and the fan
- Make sure to power the fan onto your motherboard

Over-Clocking
- Overclocking is pushing your system beyond its rated speed.
- Fans cool down CPUs. 3rd party fans are often more efficient than OEM fans
- Liquid cooling uses a pump, a radiator and a cooling block with liquid to remove heat.
- Liquid cooling reduces fan noise.

RAM Capacity—Every stick of RAM has a specific capacity.
- RAM is a square.
- RAM can be single-sided RAM or double-sided RAM versions.
- RAM uses channels which require RAM sticks to fill the channel.
- RAM should be identical capacity in the same channel.

RAM Features
- parity and ECC RAM contain extra chips to check for RAM errors.
- ECC RAM is only for motherboards that support it.
- SO-DIMMS are for smaller spaces
- Almost all RAM has a SPD (Serial Presence Detect) chip that stores information about the RAM stick.
- Tools like CPU-Z read SPD information

Installing RAM—How to install RAM memory?
- Use the motherboard book to make sure you’re installing the right capacity and RAM speed.
- Line up the notch and drop the RAM straight into the slot.
- Watch when the system boots to verify the system sees the installed RAM.
- Make sure RAM is fully installed and channels are properly filled.

RAM–Virtual Memory
- Virtual memory is a portion of mass storage that acts as memory.
- Should only be used when physical memory is exhausted.
- All operating systems have tools to adjust virtual memory use.
- In most cases we just let the OS automatically control virtual memory use (auto-control).
- SWAP file = virtual memory