Section 6 OBJ 3.2: Memory Flashcards
Random Access Memory (RAM)
Used to load applications and files into a non-persistent and fast storage area
Cache
High speed memory inside the processor
Data moves from hard disk -> memory -> cache
Mass Storage Device
permanent storage that holds more data but is slower than a cache
Disk Cache
pulls files from the disc into the memory and replaces the old file
Addressing memory
processor reaching the files inside the RAM
Data Pathway
to send and receive information
Address pathway
to determine where the data is stored
32-bit (x86) address limit
4 billion address locations
(4GB limit)
64-bit address limit
184 quintillion address locations
(16 EB)
Single bank
can put any size memory into any slot
paired bank
requires installation of banks in pairs
Dual Data Rate (DDR)
most common type of memory in modern systems
Rambus Dynamic Random Access Memory (RDRAM)
older memory in legacy systems
measured in nanoseconds
Throughput
calculated based on the bus speed and the width of the data bus
Dynamic RAM (DRAM)
oldest type of memory that requires frequent refresh
Static RAM (SRAM)
solved the issue of constant refresh from DRAM but was expensive
Synchronous DRAM
first memory module that operates at the same speed as the motherboard bus
Double Data Rate Synchronous Dynamic RAM (DDR SDRAM)
Doubles the transfer speed of a SRAM module (184-pin connector)
DDR2 SDRAM
Higher latency but has faster access to the external bus (240-pin connector)
ex: PC2-4200 means 4200 MB/s or 4.2 GB/s
DDR3 SDRAM
Runs at a lower voltage and at a higher speed than DDR2 (240 pin)
Throughput is 6.4-17 GB/s with a max size of 8GB per module
ex: PC3-10600 means 10600 MB/s or 10.6 GB/s
DDR4 SDRAM
12.8 to 25.6 GB/s of throughput
max size of 32 GB per module
PC4
DDR5 SDRAM
38.4 to 51.2 GB/s of throughput
max size of 128 GB per module
PC5
Small Outline Dual In-line memory module (SODIMM)
usually for laptops
still classified in DDR3, DDR4, or DDR5
ex: SODIMM PC4-16000
Multi-Channel Memory
Uses two different memory modules to increase the performance and throughput
Interleaving
Multiple memory modules working together to provide better performance, typically more than what each one could achieve on its own
Single-Channel
Uses one memory module on one bus (64-bit)
Dual-Channel
Uses two memory modules in two memory slots on the motherboard (128-bit data bus)
Triple-Channel
3 memory modules, 3 memory slots
192-bit data bus
Quad-Channel
4 memory modules, 4 memory slots
256-bit data bus
Error Correcting Code (ECC)
detects and corrects an error in memory
slower than parity
Non-Parity Memory
standard memory that does not check for errors and allows data to be put in or taken out
Parity Memory
performs basic error checking and ensures integrity
slower than non-parity
parity check
a basic calculation to check if data is correct and usable
parity bit
a ninth bit at the end of every byte to verify memory integrity
found by adding the value of all the bits together
can only be a 0 or 1
Buffered/Registered memory
Additional hardware (register) between memory and CPU
Virtual Memory/Page File
space on hard drive that is allocated by the OS and pretends to be memory
used when memory runs out and is a temporary solution
called page file on windows, swap space on linux
Three types of memory
Cache memory (inside CPU)
RAM/System memory
Virtual RAM/Virtual memory
