CompTIA A (Chapter 3 - CPU)

Chapter 3 - CPU:
What is a CPU?:
- Central processing units run programs

- Every CPU has internal features to process commands
- Every CPU runs code based on a specific machine language
- CPUs use pipelines to optimize the processing commands
EDB (External Data Bus) - lightbulb communication device from outside to inside the box with
the worker inside of it (enables you to communicate with the Man in the Box)
This is NOT the Kernel (Kernel is the Core of the OS!!)
Bus - Set of conductors carrying data and control signals
4 General Purpose Registers - AX; BX; CX; DX
CPU Speeds and Cores:
- CPUs have a clock speed, commonly measured in GHz (billions of cycles/sec)

- CPUs come in primarily two makes: Intel and AMD
- CPUs take a system speed and multiply it to reach the Max CPU speed
- Single CPUs often have multiple cores
Copyright Robert Mathisen & Total Seminars 2021

Intel & AMD are the main CPU companies
They have the exact same Code Book inside!
AMD Ryzen - Intel Core i9
New System Quartz Crystal
Old System Quartz Crystal

System Quartz Crystal - Rings the Bell (Silver-looking Cylinder on the Motherboard)
It’s a Quartz Oscillator that Acts as a Metronome for the entire Computer!
It’s hard to get a Motherboard that is able to keep up with these Metronome Speeds
Motherboards top out around 400MHz (expensive high-end)
(1 MHz - 1 Million Cycles per sec)
But, these CPU’s run at GHz (1 GHz - 1 Billion Cycles per sec)
Clock Multiplying - CPU will take the beat from the System Crystal & inside will multiply that beat
95% of the Clock Clicks come from inside of the CPU
This is what makes CPU’s run at incredibly high speeds!!!

Code Name “Skylake” is the name of the Microarchitecture
Base Speed = 100MHz (Motherboard Speed)
Multiplier = 35 (can slow down to a multiplier of 8, and speed up to 36)
Before buying, make sure CPU is compatible with the Motherboard.

Base Motherboard speed is set at the factory based on the System Quartz Crystals.
Multiplier is built into the CPU at the factory at Intel or AMD.
Overclocking - Special Motherboards have the ability to talk to a CPU

telling it to set the Metronome Up, but this makes systems unstable
(There would be a lot more heat coming from the CPU,
which would require the Cooling Unit to work harder too)
Just keep the “knob” where it is -no need to turn it up

Multiple Cores (Multiple Pipelines) - Handle 2 pieces of code at a time,
rather than 1 piece of code with only 1 Core/Pipeline
Hyper-Threading - Or, we could have Super Smart Pipelines

that could handle more than 1 Thread coming in.
The Prefetch would look for anyone that isn’t busy and assign the task
to anyone that can handle the task.
This made it seem as though there were multiple Pipelines!!!

Resource Monitor These 4 Cores (CPU 0-3) act as its own Independent CPU,
which is basically saying that there’s “4 lanes on the highway”
My Intel Core i5 2400 has 4 cores.

i3, i5, i7, and i9 have 2, 4, 4 (or sometimes 6-8), and 18 cores, respectively
Caching:
- CPU caching works between RAM and the CPU

- Cache is built into the CPU
- It's common to have three caches in a CPU: L1, L2, and L3
Caching - To store something closer to you for future use
A Program is copied off the Mass Storage (Hard Drive/SSD) and placed into RAM. RAM stores
that Program.

Speed: CPU > RAM > Mass Storage
This creates a Problem because the CPU is now waiting for code!!
The RAM simply can’t keep up
SRAM - Inside the CPU, we put a very small amount of very fast RAM (a few MB, whereas most
computers should have about 8GB of regular RAM)
Very expensive. We can’t use this very fast RAM to snap into our motherboard,
but in the CPU it works great!
If the Pre-Fetch is waiting for other lines of code (instruction),

the Pre-Fetch can store this waiting code in the Cache!
Pipeline Stall - This is when the CPU doesn’t have the piece of code it needs in the Cache,
resulting in the entire Pipeline shutting down. The CPU needs to retrieve it from RAM.
We want to avoid this!!!

Every CPU comes with 3 Caches
Level 1 Cache - 64K of RAM
Very Fast. It Runs at the Multiplied rate of the CPU
Level 2 Cache - 128K; 256K of RAM
This feeds the Lvl 1 Cache. Runs at Half the Clock Multiplied Speed
Level 3 Cache - #MB of RAM
Runs at the Base Motherboard Speed (a lot faster than the RAM itself)
This allows us to avoid these Pipeline Stalls!!!
Set Association - 8-way; 8-way; 4-way; 12-way

defines how the different types of Cache are Efficient at
being able to hand the right piece of code up to the CPU
Don’t mess with the Cache
AMD - VERY Big Caches Intel - Very Small Caches that are really SMART

CPU Sockets:
- CPU sockets are the mount where a CPU connects to the motherboard
- CPUS microarchitectures
- Many different CPUS come from a single microarchitecture
- There are specific CPU socket packages covered on the A+
Microarchitectures for CPU’s

(Family Names & Generations 1-8)
LGA (Land Grid Array) - Bunch of Lands on the Bottom of the Processor,
and the socket we drop it into has Pins sticking up to make the contact.
LGA 1151 Socket - Mainstream Intel CPU’s (1151 pins sticking up)
LGA 2066 Socket - Very High-End CPU’s (Intel i9)
PGA (Pin Grid Array) - Bunch of Pins sticking out of the Bottom of the Processor
AM4 Socket - Mainstream AMD CPU’s TR4 Socket - Very High-End AMD CPU’s

Installing a CPU:
- Make sure you have the right socket and speed CPU for your motherboard
- Always use thermal paste between the CPU and the fan
- Connect the fan to a power source
Buy the Motherboard & CPU at the same time

CPU needs to be compatible with the CPU Socket on the Motherboard!!
Drop the CPU in the Socket so that the

3 triangle notches and the 1 square notch are in the correct orientation with the Socket!
One way to see if the fan is installed correctly -try to pick up the fan (motherboard should follow)

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Chapter 3 - CPU:

- Central processing units run programs

CPU Speeds and Cores:

- CPUs have a clock speed, commonly measured in GHz (billions of cycles/sec)

Copyright Robert Mathisen & Total Seminars 2021

New System Quartz Crystal

Old System Quartz Crystal

Copyright Robert Mathisen & Total Seminars 2021

Before buying, make sure CPU is compatible with the Motherboard.

Overclocking - Special Motherboards have the ability to talk to a CPU

Copyright Robert Mathisen & Total Seminars 2021

Hyper-Threading - Or, we could have Super Smart Pipelines

Copyright Robert Mathisen & Total Seminars 2021

My Intel Core i5 2400 has 4 cores.

- CPU caching works between RAM and the CPU

Caching - To store something closer to you for future use

Copyright Robert Mathisen & Total Seminars 2021

If the Pre-Fetch is waiting for other lines of code (instruction),

Copyright Robert Mathisen & Total Seminars 2021

This allows us to avoid these Pipeline Stalls!!!

Set Association - 8-way; 8-way; 4-way; 12-way

Don’t mess with the Cache

Copyright Robert Mathisen & Total Seminars 2021

Microarchitectures for CPU’s

Copyright Robert Mathisen & Total Seminars 2021

Buy the Motherboard & CPU at the same time

Drop the CPU in the Socket so that the

Copyright Robert Mathisen & Total Seminars 2021

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