WGU D386 Final Exam Study Guide: Key Concepts &
Technologies Overview-Graded A
Operating Systems:
. Operating system (OS) – program that manages and coordinates the activity and sharing of computer
resources
Multiple Types:
. Personal computer OS – manages the resources (CPU, memory, hard drive, peripherals, etc.) of a
computer
- Provides a GUI for the user to
navigate Examples: Windows, Mac, Linux, etc.
. Server OS – designed to manage the resources of a server
- Uses a command line interface (CLI) of GUI to control applications and
services Examples: Windows Server, Linux, and Unix
. Embedded OS – designed to manage the resources of a device (sensor, controller, other internet of
things (IoT) devices-like a fridge or microwave)
- Provide a light-weight kernel that runs on low-powered
hardware Examples: FreeRTOS and VxWorks
. Mobile OS – duh
Examples: iOS and Android
RAM:
. Memory - a hardware device used to store computer programs, instructions, and data
. RAM - Temporary, volatile memory store on the motherboard in DIMMs
- Holds system code and other programs
. DIMM (dual memory in-line module) – module connected to the motherboard’s memory slots w/ pins
and “dual” because there are 2 separate rows of these pins that are different from one another
- Used in desktop computers and servers
- Usually >= 240 pins and support higher mem capacity and speeds vs. SODIMM
. SODIMM (Small Outline DIMM) – Smaller version of DIMM used in laptops, compact desktops, and
other small form factor systems
- Usually <= 204
pins Process:
, 1. Data and programs stored on the hard drive are loaded into RAM
2. Once in RAM, the CPU can access the data/run the program
Higher RAM increases performance since the data does not need to be constantly fetched from the hard
drive and sent to RAM, since RAM can hold more data and is faster than fetching from the hard drive
RAM comes in 3 main types:
1. DRAM (dynamic RAM) – stores bits of data in capacitors that need to constantly be refreshed,
hence ‘dynamic’ (capacitors leak)
- Operates asynchronously from the clock cycle
- Slower than SDRAM
2. SDRAM (synchronous DRAM) – Runs in sync with the system clock
- Faster than DRAM
3. Virtual RAM (VRAM) – the process of transferring data from RAM to disk storage
- referred to as a “paging file” on Windows and “Swap Space” on Mac/Linux
- mapping memory chunks to disk files allows the secondary/external memory (drives that hold
data permanently (SSD/HDD)) to be treated like primary memory (RAM)
- used to compensate for insufficient RAM during heavy multitasking or resource intensive processes
- frees up RAM by swapping data that hasn’t been used recently over to a storage device
(HHD/SSD) Concept:
64 or 32 bit data path refers to the amount of bits transferred per clock cycle (more is faster)
- All DIMM are 64 bit
. DDR (double data rate) – doubles the speed of RAM by sending data on the rising and falling edge of the
clock signal (clock signals are timed electrical pulses)
- Regular DDR has 184 pins
- 2X faster than
SDRAM Multiple generations
of DDR:
*All DDR is SDRAM*
. DDR2 – faster and more power efficient than DDR – has 240 pins
. DDR3 – twice as fast as DDR2 and uses even less power – 240 pins – notches to attach to motherboard are
in different places
. DDR4 – 288 pins, higher speeds, and uses less power
. DDR5 - doubles the speed of DDR4 to 6.4 Gbps
Some RAM cannot afford to lose any data (think hospital servers) so it has error correcting code (ecc)
, . ECC – code that checks that data was processed correctly and makes any needed corrections
Cache Memory:
. Static RAM (SRAM) – type of memory that is used in CPU cache and doesn’t need to be refreshed
(hence, static vs dynamic)
- Faster and more expensive than DRAM
. CPU Cache – stores copies of data and instructions from RAM that’s waiting to be used by the CPU
which allows it to access that data more quickly
- Faster than RAM (CPUs process data faster than RAM can feed it to the CPU)
- Acts as a buffer between the CPU and
RAM Levels of cache:
. Level 1/primary cache – located on the actual CPU
- Runs at the same speed as the processor and is the fastest cache on a computer
- Dedicated to it’s own CPU core
. Level 2 – used to catch recent data accesses from the processor not caught by level 1 cache
- Located on the processor, slower, and larger than level 1 cache
- Dedicated to its own CPU core
Level 3 – catches recent data accesses from the processor that level 2 missed
- Also located on the processor, slower, and larger than level 2 cache
- Shared between all CPU cores
*If the needed data is not found in cache L1, L2, or L3, the CPU will go to the RAM for the data*
CPU:
. CPU – principal part of any digital computer system, generally composed of the main memory, control
unit, and arithmetic-logic unit and processes program instructions for output via the instruction cycle.
CPU Components:
. Arithmetic Logic Unit (ALU) - performs arithmetic, logical, and bitwise operations on integer binary
numbers
. Registers – the smallest data holding elements that are built into the processor itself. These are the
memory locations that are directly accessible by the processor
Technologies Overview-Graded A
Operating Systems:
. Operating system (OS) – program that manages and coordinates the activity and sharing of computer
resources
Multiple Types:
. Personal computer OS – manages the resources (CPU, memory, hard drive, peripherals, etc.) of a
computer
- Provides a GUI for the user to
navigate Examples: Windows, Mac, Linux, etc.
. Server OS – designed to manage the resources of a server
- Uses a command line interface (CLI) of GUI to control applications and
services Examples: Windows Server, Linux, and Unix
. Embedded OS – designed to manage the resources of a device (sensor, controller, other internet of
things (IoT) devices-like a fridge or microwave)
- Provide a light-weight kernel that runs on low-powered
hardware Examples: FreeRTOS and VxWorks
. Mobile OS – duh
Examples: iOS and Android
RAM:
. Memory - a hardware device used to store computer programs, instructions, and data
. RAM - Temporary, volatile memory store on the motherboard in DIMMs
- Holds system code and other programs
. DIMM (dual memory in-line module) – module connected to the motherboard’s memory slots w/ pins
and “dual” because there are 2 separate rows of these pins that are different from one another
- Used in desktop computers and servers
- Usually >= 240 pins and support higher mem capacity and speeds vs. SODIMM
. SODIMM (Small Outline DIMM) – Smaller version of DIMM used in laptops, compact desktops, and
other small form factor systems
- Usually <= 204
pins Process:
, 1. Data and programs stored on the hard drive are loaded into RAM
2. Once in RAM, the CPU can access the data/run the program
Higher RAM increases performance since the data does not need to be constantly fetched from the hard
drive and sent to RAM, since RAM can hold more data and is faster than fetching from the hard drive
RAM comes in 3 main types:
1. DRAM (dynamic RAM) – stores bits of data in capacitors that need to constantly be refreshed,
hence ‘dynamic’ (capacitors leak)
- Operates asynchronously from the clock cycle
- Slower than SDRAM
2. SDRAM (synchronous DRAM) – Runs in sync with the system clock
- Faster than DRAM
3. Virtual RAM (VRAM) – the process of transferring data from RAM to disk storage
- referred to as a “paging file” on Windows and “Swap Space” on Mac/Linux
- mapping memory chunks to disk files allows the secondary/external memory (drives that hold
data permanently (SSD/HDD)) to be treated like primary memory (RAM)
- used to compensate for insufficient RAM during heavy multitasking or resource intensive processes
- frees up RAM by swapping data that hasn’t been used recently over to a storage device
(HHD/SSD) Concept:
64 or 32 bit data path refers to the amount of bits transferred per clock cycle (more is faster)
- All DIMM are 64 bit
. DDR (double data rate) – doubles the speed of RAM by sending data on the rising and falling edge of the
clock signal (clock signals are timed electrical pulses)
- Regular DDR has 184 pins
- 2X faster than
SDRAM Multiple generations
of DDR:
*All DDR is SDRAM*
. DDR2 – faster and more power efficient than DDR – has 240 pins
. DDR3 – twice as fast as DDR2 and uses even less power – 240 pins – notches to attach to motherboard are
in different places
. DDR4 – 288 pins, higher speeds, and uses less power
. DDR5 - doubles the speed of DDR4 to 6.4 Gbps
Some RAM cannot afford to lose any data (think hospital servers) so it has error correcting code (ecc)
, . ECC – code that checks that data was processed correctly and makes any needed corrections
Cache Memory:
. Static RAM (SRAM) – type of memory that is used in CPU cache and doesn’t need to be refreshed
(hence, static vs dynamic)
- Faster and more expensive than DRAM
. CPU Cache – stores copies of data and instructions from RAM that’s waiting to be used by the CPU
which allows it to access that data more quickly
- Faster than RAM (CPUs process data faster than RAM can feed it to the CPU)
- Acts as a buffer between the CPU and
RAM Levels of cache:
. Level 1/primary cache – located on the actual CPU
- Runs at the same speed as the processor and is the fastest cache on a computer
- Dedicated to it’s own CPU core
. Level 2 – used to catch recent data accesses from the processor not caught by level 1 cache
- Located on the processor, slower, and larger than level 1 cache
- Dedicated to its own CPU core
Level 3 – catches recent data accesses from the processor that level 2 missed
- Also located on the processor, slower, and larger than level 2 cache
- Shared between all CPU cores
*If the needed data is not found in cache L1, L2, or L3, the CPU will go to the RAM for the data*
CPU:
. CPU – principal part of any digital computer system, generally composed of the main memory, control
unit, and arithmetic-logic unit and processes program instructions for output via the instruction cycle.
CPU Components:
. Arithmetic Logic Unit (ALU) - performs arithmetic, logical, and bitwise operations on integer binary
numbers
. Registers – the smallest data holding elements that are built into the processor itself. These are the
memory locations that are directly accessible by the processor
