Cache Memory Levels

L1 Cache Proximity

Closest to CPU Cores

L1 Cache Speed

Fastest among all cache levels due to proximity and high speed SRAM technology

L1 Cache Size

Smallest in size

16KB - 128 KB per core

L1 Cache Purpose

Primarily stores frequently accessed data and instructions to reduce latency and improve the CPU’s processing speed

L1 Cache Structure

Often split into 2 separate caches

• L1i - for instructions

• L1d - for data

L2 Cache Proximity

Sits between L1 Cache and RAM

L2 Cache Speed

Slower than L1 but faster than L3 cache and RAM

L2 Cache Size

Larger than L1

256KB - Several MB per core

L2 Cache Purpose

Acts as an intermediary between L1 and L3

Holds data and instructions that are less frequently accessed than those in L1, but more than RAM

L2 Cache Structure

Can be unified or split

unified = stores both data and instructions

split = similar to L1

L3 Cache Proximity

Shared among multiple CPU cores within the same processor

L3 Cache Speed

Slower than L2 but faster than RAM

L3 Cache Size

Larger than L2

Ranges from a few MB to tens of MB

L3 Cache Purpose

Provides a larger shared cache that can store data and instructions

Accessible by all cores, reducing the need to fetch from slower main memory (RAM)

L3 Cache Structure

Usually unified, storing both data and instruction

Clock Speed

Measured in GHz

Indicates the number of cycles a CPU can perform per second

Core Count

More cores allow for better multitasking and parallel processing

Hyper-threading/Simultaneous Multithreading (SMT)

Allows each core to handle multiple threads

Thermal Design Power (TDP)

Indicates the amount of heat a CPU generates, affecting cooling requirements

General Purpose CPUs

Designed for everyday tasks

• Web browsing

• Office applications

• Multimedia consumption

Examples:

• Intel Core i3, i5

• AMD Ryzen 3

High-Performance CPUs

• Gaming

• Video editing

• Intensive tasks

• High clock speeds

• More cores/threads

• Larger cache sizes

Examples:

• Intel Core i7, i9

• AMD Ryzen 7, 9 Series

Server CPUs

Enterprise CPUs and Blade Serves/Microservers

Enterprise CPUs

Designed for

• Data centers

• High performance computing environments

• Large caches

• Support for multi-processor configurations

Examples:

• Intel Xeon

• AMD EPYC processors

Blade Servers and Microservers

• Used in compact and scalable server environments

• Optimized for density and power efficiency

Mobile CPUs

Smartphones and Tablets: Prioritize power efficiency and integrated graphics capabilities

Laptops: Mobile CPUs for laptops balance performance and battery life

Embedded CPUs

Microcontrollers/System-on-Chip (SOC) and Raspberry Pi and Similar boards

Microcontrollers/System-on-Chip (SOC)

Used in:

• IoT devices

• Automotive systems

• Industrial applications

• Highly integrated with peripherals and memory

Examples:

• ARM Cortex-M, Cortex-A

• Atmel AVR

Raspberry Pi

Use ARM based CPUs like Broadcom BCM series

High-End Workstation CPUs

Designed for:

• 3D rendering

• Scientific simulations

• Professional applications

Examples:

• Intel Xeon W

• AMD Threadripper

Gaming Consoles

Used for:

• Gaming

• Balancing CPU and GPU performance

Examples:

• AMD custom processors used in Playstation and Xbox consoles

Supercomputers

High performance CPUs

• Used in supercomputing clusters

• High core counts

• Support for parallel processing

Examples:

• IBM POWER Processors

• Intel Xeon Phi

CPU Related Issues: High CPU Usage

Symptoms:

• Slow system performance

• Overheating

• System lag

• Reduced battery life on laptops

Solution:

• Close unnecessary programs

• Optimize software

• Upgrade hardware

• Scheduled maintenance

CPU Related Issues: Overheating CPU

Symptoms:

• System shutdowns

• Reduced performance due to thermal throttling

• Potentially permanent damage to the CPU

Solution:

• Improve cooling systems

• Optimize CPU airflow

• Monitor temperatures

• Cooling pads under laptops

CPU Related Issues: CPU Bottleneck

Symptoms:

• Inability to fully utilize high-end GPUs or other hardware components

• Poor performance in games and applications despite having good hardware

Solution:

• Ensure a balanced configuration of CPU, GPU, and RAM

• Adjust settings to reduce CPU load

• Upgrade to a better CPU

• Carefully overclock the CPU to increase performance

CPU Related Issues: CPU Failure

Symptoms:

• System will not boot

• Frequent crashes

• Unusual noises

Solution

• Confirm the issue is with the CPU by testing other components such as

  • RAM

  • GPU

  • Motherboard

• Check physical connections

• Inspect for physical damage

• Test power supply

• Reset and/or update BIOS/UEFI

Control Unit Function

• Directs the operations of the processor

• Tells the computer’s memory, ALU, and I/O devices how to respond to the instructions that have been sent to the processor

Control Unit Importance

• Coordinates how data moves around the CPU

• Controls the flow of data between the CPU and other components of the computer

Registers

• Small, fast storage locations within the CPU that hold data and instructions temporarily

• Provide quick access to frequently used data and instructions

• Enhance processing speeds

Types of Registers: Accumulator (ACC)

• A register that stores the results of the arithmetic and logical operations performed by the CPU’s ALU

Types of Registers: Program Counter (PC)

• A register that holds the memory address of the next instruction to be fetched and executed by the CPU

Types of Registers: Memory Address Register (MAR)

• A register that holds the memory address of the data or instruction being accessed or manipulated in the computer’s memory

Types of Registers: Memory Data Register (MDR)

• A register that temporarily holds the data fetched from or to be written to the computer’s memory

Arithmetic Logic Unit (ALU)

• Performs arithmetic and logical operations

  • Addition, subtraction, multiplication, division, AND, OR, NOT, XOR, etc.

• Essential for executing mathematical calculations and decision-making processes

GPU

• A specialized electronic circuit designed to accelerate the processing of images and videos.

• Particularly efficient at handling tasks that involve parallel processing, where many calculations can be performed simultaneously

Integrated GPU

• Built into the CPU and share the systems RAM

  • Sufficient for tasks like web browsing, office applications, and some light gaming

Dedicated GPU

• Separate cards installed in the system, with their own VRAM.

• Much more powerful and suitable for demanding tasks

Use Cases for GPU

• Gaming

  • Essential for rendering complex graphics

• Video Editing and Rendering

  • 3D rendering

  • Animation

• Scientific Computing

  • Simulations

  • Data Analysis

  • Computational tasks that require massive parallel processing, such as climate modeling, molecular dynamics, and astrophysics

• Machine Learning and AI

  • Good for training models on large datasets

  • GPUs speed up the process due to their parallel processing capabilities

• Professional Applications

  • Architecture

  • Engineering

  • Design

  • Used for CAD (Computer Aided Design) applications

Pipelining (CPU Function)

A hardware technique to increase the instruction throughput of a CPU by overlapping instruction execution stages

Step 1 - Pipelining - “Fetch”

Retrieving the instruction from memory

Step 2 - Pipelining - “Decode”

Interpreting the instruction and preparing the necessary control signals

Step 3 - Pipelining - “Execute”

Performing the operation specified by the instruction (arithmetic or logic operations)

Step 4 - Pipelining - “Memory Access”

Reading from or writing to memory, if required by the instruction

Step 5 - Pipelining - “Write Back”

Writing the result back to the register file

Multithreading (Application Function)

Executing multiple threads within a single process concurrently, improving CPU utilization and performance for multithreaded applications

Thread

• The smallest unit of execution within a process

• A process can contain multiple threads, each running independently but sharing the same resources, such as memory and file handles

Multithreading - Improved Performance

• Can improve performance of applications, especially on multi-core processors

Multithreading - Resource Sharing

Threads within the same process share resources like memory and data, which leads to more efficient use of resources

Parallelism

Executing multiple threads simultaneously

Multitasking (OS Function)

OS level feature that allows multiple processes to run concurrently, providing the ability to run multiple applications at the same time

Preemptive Multitasking

• OS determines when a process should pause to allow another process to execute

• Allocates time slices to each process

• Ensures fair distribution of CPU time

• Prevents any single process from monopolizing the CPU

• Improves responsiveness

Cooperative Multitasking

• Each process voluntarily yields control to allow other processes to run

• Processes must be designed to provide time to the OS

• Early versions of Window and classic Mac OS used this

• Disadvantage: If a process does not yield control control, it can lead to system unresponsiveness or crashes

RAM (Random Access Memory)

Stores data and instructions that the CPU needs quickly

ARAM (Asynchronous RAM)

• A type of RAM where memory operations are not synchronized to a clock signal

• Each operation (read or write) is initiated independently and can occur at any time without needing to wait for a clock edge

DRAM (Dynamic Random Access Memory)

• A type of ARAM that:

  • Must be refreshed periodically to preserve the stores data

  • Use: General purpose memory for computers and other devices

  • Pins: Varies, early DRAM used DIP packages with 16 or 18 pins

SRAM (Static Random Access Memory)

• A type of ARAM that:

  • Data is not stored as charge on a capacitor, but in a pair of cross-couples inverters

  • Does not need to be refreshed

  • Use: Cache memory in CPUs, small amounts of fast memory

  • Pins: Varies

SDRAM (Synchronous DRAM)

• A type of computer memory that is synchronized with the system bus

• Allows for faster data transfer rates

• Use: Main memory in older computers and graphics cards

SDR (Single Data Rate)

• A type of SDRAM that:

  • Pins: 168

  • Data Rate: Once per clock cycle

  • Usage: Older desktop/laptop computers

DDR (Double Data Rate)

• A type of SDRAM that:

  • Pins: 184

  • Data Rate: 2x per clock cycle

  • Usage: Early 2000s desktop and laptop computers

DDR2

• Pins: 240

• Data Rate: 2x per clock cycle, but with improved speed and efficiency over DDR

• Latency: Lower latency compared to DDR

• Usage: Mid 2000s desktop/laptops

DDR3

• Pins: 240

• Data Rate: 2x per clock cycle with further improvements over DDR2

• Latency: Better than DDR2

• Usage: Late 2000s to mid 2010s desktop/laptop/servers

DDR4

• Pins: 288

• Data Rate: 2x per clock cycle with further enhancements

• Latency: Improved latency and power efficiency compared to DDR3

• Usage: Mid 2010’s to present day desktop, laptop, servers

DDR5

• Pins: 288

• Data Rate: 2x per clock cycle with significant improvements

• Latency: Further improvements in latency, power efficiency, and increased density compared to DDR4

• Usage: High performance computing, modern desktop, laptop, servers

Virtual RAM

• AKA: Virtual memory

• Memory management technique used by OS to extend the apparent amount of RAM available to applications

• Done by using a portion of a computer’s storage (such as an SSD or HDD) to simulate additional RAM

Virtual RAM - Paging

• The OS divides physical memory and virtual memory into small fixed-sized blocks called pages

• When the system runs out of physical RAM, it can swap inactive pages to the storage device, freeing up RAM for active processes

Virtual RAM - Pagefile/Swap Space

• File or partition on the storage device

• Used to store pages that are moved out of physical RAM

Virtual RAM - Address Translation

• The CPU uses a memory management unit (MMU) to translate virtual addresses (used by programs) into physical addresses (used by the hardware)

• Allows applications to use more memory than is physically available

RAM Related Issues - Insufficient RAM

• Symptoms

  • Slow performance

  • Frequent freezing

  • Slow response times when opening apps

  • Excessive hard drive activity due to increased paging/swap file usage

• Solution

  • Upgrade RAM to handle the memory demands of multiple design applications

RAM Related Issues - Faulty RAM

• Symptoms

  • Random system crashes

  • Blue screens of death (BSODs)

  • Data corruption

  • Errors during software installation or while running programs

• Solution

  • Swap or replace faulty RAM

  • If you have multiple RAM modules, test each one individually by removing all but one and booting the computer

RAM Related Issues - Incompatible RAM

• Symptoms

  • System fails to boot

  • Constant reboots

  • BIOS does not recognize installed RAM

• Solution

  • Make sure the RAM is installed correctly

  • Make sure there is no physical damage

  • Replace the RAM if it is not compatible with the motherboard specification

RAM Related Issues - Memory Leaks

• Symptoms

  • Gradual decrease in available memory

  • System slows down over time

  • Applications may crash or freeze

• Solution

  • Look for improper memory allocation and deallocation patterns

ROM (Read Only Memory)

• Non-volatile memory used in computers and other electronic devices

• Unlike RAM, which is volatile and loses its data when the power is turned off,

  • ROM retains its data even when the device is powered down

• Makes ROM ideal for storing firmware, which is software that is closely tied to specific hardware and unlikely to need frequent updates

Types of ROM - Masked ROM (MROM)

• Original form of ROM

• Data is written during the manufacturing process and cannot be altered

• Used for simple, unchangeable firmware

Types of ROM - Programmable ROM (PROM)

• Can be written once after manufacturing

• Data is programmed using a special device called a PROM programmer

Types of ROM - Erasable Programmable ROM (EPROM)

• Can be erased by exposing it to ultraviolet light and then reprogrammed

• Allows for the modification of data if needed, but the process is not simple

Types of ROM - Electrically Erasable Programmable ROM (EEPROM)

• Can be erased and reprogrammed using an electrical charge

• More flexible than EPROM

• Allows for byte level modification and is commonly used for firmware updates

Types of ROM - Flash Memory

• A type of EEPROM that can be erased and reprogrammed in blocks

• Widely used in USB drives, SSDs, and memory cards

• Can retain data without power and supports frequent rewrites

RAM VS. ROM

• Volatility: RAM is volatile, ROM is non-volatile

• Usage: RAM is used for temporary storage of data in use, ROM is used for permanent storage of firmware

• Read/Write: RAM can be read and written to easily, ROM is primarily read only

• Speed: RAM is faster than ROM

• Capacity: RAM typically has larger capacities compared to ROM

Motherboard

• Also known as a mainboard

• Crucial component in any computer system

• Serves as the central hub that connects various hardware components and allows them to communicate with each other

Motherboard: Chipset

• A set of integrated circuits that manage data flow between the CPU, memory, storage devices, and peripherals

• Includes the Northbridge and Southbridge

Motherboard: Northbridge

• Responsible for highspeed peripherals

Northbridge: CPU Socket

• Where the CPU is installed

• Socket type determines which CPUs are compatible with motherboard

Northbridge: RAM Slots

• Hold RAM modules

Northbridge: Expansion Slots

• Allow you to install expansion cards such as:

  • Graphics cards (PCIe)

  • Sound cards

  • Network cards

  • Storage controllers

• Common slot types:

  • PCIe x16

  • PCIe x1

  • Legacy slots like PCI

Northbridge: Integrated Graphics

• GPU integrated into the motherboard

Motherboard: Southbridge

• Slow peripherals

Southbridge: Storage Interfaces

• Come with various storage interfaces for connecting hard drives (HDDs), solid-state drives (SSDs), and optical drives

• SATA (Serial ATA) and M.2 are common interfaces for modern storage devices

Southbridge: BIOS/UEFI Chip

• Contains the Basic Input/Output System (BIOS) or Unified Extensible Firmware Interface (UEFI), which provides the firmware interface for initializing hardware during the boot process and configuring system settings

Southbridge: I/O Ports

• Located on the rear I/O panel of the motherboard and include:

  • USB ports

  • Audio jacks

  • Ethernet ports

  • Video outputs (if motherboard has integrated graphics)

  • Other connectors for peripherals

Southbridge: Fan Headers

• Headers for connecting:

  • CPU fans

  • Case fans

  • Other cooling devices

• To regulate system temperature

Southbridge: CMOS Battery

• Small battery

• Powers the CMOS (Complementary Metal-Oxide Semiconductor) memory

  • Stores BIOS/EUFI settings and system configurations even when the computer is powered off