System Memory Flashcards
Cache
- High-speed memory
- Inside the processor
- Small amount of space
- Extremely fast
Storage
4
- Mass storage device that holds more data
- slower than a cache
- Ex: HD, USB drive, CD, DVD, etc.
- Mass storage (Persistent or Permanent storage)
Disk Cache
- Pulls the files from the disc into memory and replaces the old file
- put them back on mass storage when your done
- Allows quicker operations
RAM
8
Random Access Memory (RAM)/ System Memory/ Memory
- Temporary Storage (Non-persistent storage)
- When you power off the computer everything in RAM will be lost
- Operates fast
- Ex: Desktop is like RAM where everything is easily accessible (Pens, note pads,etc.)and your storage cabinet is like mass storage
- Solid state device
- operating speed is in Nano seconds
- by increasing RAM you can speed up your system
Mechanical system
1
- Uses an electronic system that can access the RAM with instant speed
Addressing memory
2/ Like home
- Processor reaching for the files inside RAM
- Data is given a unique identifier to be able to locate it within the memory
Bus
- A pathway to transfer data
- There are two parts of the bus
1. The pathway used for data and to send & receive information
2. Address pathway to help determine where in the memory it’s located - width of the data pathway/of the bus this is going to determine how much data can be transferred with each clock cycle (64 bit, 32 bit
Memory controller
1
- Tells the CPU and processor how to access different parts of the memory
32 bit CPU (x86 CPU)
5
- Can only use 32-bit address to access data over that memory bus
- 4 billion address locations (4GB of data)
- 2^32
- x86 or 32 bit processor you can only use 4GB of RAM
- Memory is a huge limitation b/c most modern operating systems use a minimum of 4GB of RAM (Memory) to operate sufficiently
64 bit CPU (x64 CPU)
6
- Can use 64-bit address to access data over that memory bus
184 quintillion address locations (16 Exabytes (EB) of data) - 2^64
- Most systems don’t use and is expensive, not enough space
- Can access more than 4 GB of RAM (Memory)(8,16, 32, or 64GB)
- better to use over 32 bit b/c more RAM (More RAM = better performance)
Memory modules
7
- Type of memory is going to be determined by the motherboard and it’s form factor
- Best practice is to check your motherboard manual for the proper type, size, keying (fit), and speed of memory (If it supports 16 GB you can use 4, 8, or 16 GB modules) (Can only use what your form factor supports
- Some motherboards memory module allow you to mix sizes (8 GB in slot one and 4 GB in slot 2)
- motherboard will use the slower speed of the modules used (Ex: 38. 4 and 51.2 GB/s mother board will operate at the slower speed.
- always buy in pairs
- some require require memory modules to be the same size (Capacity 4, 8, 16 GB)
- memory modules vary by type
Single bank
1
- Can put any size of module in any slot
Paired bank
1
a set of two memory modules that are installed in the same channel of a computer’s motherboard to work together in dual-channel mode
DDR
Double data rate
-each one will not fit into each others slot
-B/c the knotches are in different places
Throughput
- Calculated based on the bus speed and the width of the data bus
- Most modern memory is measured in throughput
- EX: if using
- 3:45
DRAM
5
- Dynamic RAM
- Oldest type of memory that requires frequent refreshing
- Requires frequent refresh to make sure it wasn’t lost
- Stores each bit of data in a storage cell (storage cells consists of a capacitor and transistor) and organized in a rectangular configuration of different storage cells
- DRAM storage cell is dynamic meaning it needs to be refreshed or given a new electrical charge every few milliseconds to compensate for the charge leaks otherwise data stored in DRAM will get lost
SRAM
3
Static RAM
- Solved the issue of constant refresh but was expensive.
- Only used in high speed needs (L1, L2, L3 CPU caches, Hard disk buffers and LCD screens buffers
SDRAM
3
- Synchronous DRAM
- first memory module that operated at the same speed as the motherboards bus
- Initial chips were 168-pin Dual in-line Memory modules (DIMM) and speeds measured in megaherts (MHz)
Common naming conventions for these
- PC66 (66 MHz bus)
PC133 (133 MHz bus)
PC266 (266 MHz bus)
DDR2 SDRAM
- Double Data Rate 2 Synchronous Dynamic Random-Access Memory (DDR2
SDRAM) - Doubles the transfer rate of a SRAM module
- 184 pin connector
- Rated in MB/s in thorughput
- PC2-1600 (1.6 MB/s of throughput)
DDR2 SDRAM
5
Double Data Rate 2 Synchronous Dynamic Random-Access Memory (DDR2
SDRAM)
- Higher latency and has faster access to the external bus (240-pin connector)
- can transfer data two times per clock cycle
- rated in MBps as their throughput
Common naming conventions
- PC2-4200 (4200 MB/s or 4.2 GB/s of throughput
DDR3 SDRAM
8
- Double Data Rate 3 Synchronous Dynamic Random-Access Memory (DDR3
SDRAM) - Runs at a lower voltage and at a higher speed than DDR2 (240 keyed pin
connector) - each module is keyed (Knotch)
- not backwards compatible with DDR2
- Normally going to see data transfer rates or throughput of 6.7 to 17 GB/s
- maximum module size of 8GB per memory module
common naming conventions - PC3-10600 MB/s or 10.6 GB/s of throughput
- Install module straight into MB at a 90 degree angle against the MB
- standard for desktops
DDR4 SDRAM
- Double Data Rate 4 Synchronous Dynamic Random-Access Memory (DDR3
SDRAM) - 12.8 to 25.6 GB/s of throughput
- Maximum module size 32 GB per module
PC4-16000 (16,000 MB or 16 GB) - Install module straight into MB at a 90 degree angle against the MB
- standard for desktops
DDR5 SDRAM
6
- Double Data Rate 5 Synchronous Dynamic Random-Access Memory (DDR5
SDRAM) - 38.4 to 51.2 GB/s of throughput
- 128 GB per module
- PC5-42000 (42,000 MB/s or 42 GB/s)
- standard for desktops
- has internal error checking. this is not ECC or an ECC module. can be used on motherboards without ECC and in turn have capability for error checking (Not considered ECC)
- DDR5 modules can still be sold as ECC or non-ECC ( because it can use its own internal error checking to work with ECC)
- for the test be able to look at the naming conventions and identify the MB/s and GB/s
- Install module straight into Mother Board at a 90 degree angle against the MB
SODIMM
5
- Small Outline Dual In-line Memory Module (SODIMM)
- Common naming conventions with SODIMM in front.
SODIMM PC4-16000 (16000 MB/s or 16 GB/s) (EX:DDR4 SODIMM PC4-16000) - standard for laptops
- Still classified as DDR, DDR3, DDR4, DDR5
Installing - insert at a 45 degree angle angle and then push down flat against mother board and it will be locked into pace using reattaining clips
Multi-Channel Memory
- Multiple modules give you faster speeds and add memory for storage
- Use two different memory modules at the same time in tandem to increase the performance and throughput
- When configuring dual, triple, or quad its important to check your motherboards manual first because every motherboard is a little bit different in how they set them up
- Just because it has four slots doesn’t mean it supports quad-channel it may only support single or dual
- Generally when you’re looking at the slots on your mother board they will be label as 0,1,2,3, and 4 or A0, A1, or B0, and B1 if doing in banks
- its important to check your manual to know where the slot are to insert memory modules
- its best practice to use the same model. speed. and throughput of memory in all the slots that are going to be apart of the same multi-channel working together
- Ex: if you have four slots in your Motherboard while operating in dual channel configuration and using those slots together you want to make sure the memory module in both slots is the same size (8 or GB) and same speed such as 16000 or 32000 MB/s to make sure there are no compatibility issues going forward.
Single- channel memory
- Uses one 64-bit data pathway (bus) between the processor memory controller, and the RAM modules
Dual-Channel Memory
3
- Uses two 64-bit (128 bit) data pathway (bus) between the processor, memory controller, and the RAM modules
- Requires two memory modules and two memory slots on the Motherboard
- Interleaving gives you increased performance. The sum total of both can access more than either one can do individually
-ex: (Two horses pulling 100lb by themselves but 250LBS together)
Multi-Channel Memory Types
4
- Single
- Dual
- Triple
- Quad
Triple-Channel Memory
3
- Uses three memory modules
- three memory slots
- 192-bit data bus
Quad-Channel Memory
3
- Uses four memory modules
- four memory slots
- 256-bit data bus
Non-Parity Memory
opposite of Parity Memory
- Standard memory that does not check for errors and allows data to be put in or taken out
- What most memory is going to be
- It’s cheap
- higher speed than parity
Parity Memory
4
- Performs basic error checking and ensures the memory contents are reliable
- slower than non-parity
- Has the reliability needed for server and high-end workstations
- Parity check
Parity Check
- Memory that does basic calculation based on what it’s seeing to verify if the data is good or not.
- if the data is good it will use it and if not an error will occur but it wont be able to fix it. it can only tell you there’s an error.
Every byte has an…..
4
- Associated parity bit
- Instead of having 8 bits (8 bits =1 byte) you now have 9 bits. 8 data bit + 1 for parity
- Parity bit is going to set at write time then its going to be calculated and compared to determine if any of the bits have changed since the data was last written into the memory
- this type of checking is limited to the single-bit errors and if there is two bits that were altered the parity check may pass
Parity error
2
000000000
000000001
- Zeros added together equal zero but there is a one below so the data was changed.
- you wont be able to detect if two or more were changed with a parity type calculation because it can only detect one.
- 90% of most errors are singal bit.
If you add up your bits and they are an odd number
its a 1 parity bit
If you add up your bits and they are an even number
- it is 0 parity bit
ECC
10
Error correcting code
- Detects and corrects an error
- slower than parity and non-parity
- giving up performance but get integrity and higher reliability when using ECC
- your only going to see ecc in high-end workstations or servers because of cost and extra high level of integrity Is only needed in those types of environments
- how does it work? uses buffered memory
- motherboard and CPU has to support. if either don’t you wont get that benefit
- most motherboard support ECC or they don’t
- if your motherboard supports ECC your going to have to buy ECC modules which are registered modules
- if you do find a motherboard that supports ECC or non ECC they wont support both at the same time. all your modules have to be ECC or none can be ECC (mixtures causes errors and motherboard wont know how to handle
Buffered/ Registered Memory
3
- Additional hardware (register) between memory and CPU
- The system requires buffereing or registering the data to reduce the electrical load used by systems that have large amounts of memory modules
- can be paired with parity or ECC
Virtual Memory (VRAM)
6
Virtual Memory (VRAM):
Virtual memory is a space on a storage device (e.g., hard drive or SSD) allocated by the operating system to simulate additional RAM when physical memory (RAM) is insufficient or running slowly.
Key points:
- Implemented as a hidden file called a Page File on Windows or swap space on Linux, Unix, and macOS.
- It allows the system to handle more data than the available physical RAM by swapping data in and out of storage.
- Memory is managed in 4 KB chunks called “pages,” which optimize memory allocation for processes.
- Relying heavily on virtual memory can slow the system, as frequent swapping leads to increased drive activity (“disk thrashing”).
- You can increase the size of the page file or swap space as a temporary solution to alleviate memory limitations.
Installing memory
5
- Put on electro static wrist strap
- Check motherboard manual before installing
- Look for knotch and line up with motherboard. will only go in one direction (90 degree angle to the mortherboard
- slide into place until click
- lock latch into position against the module.
