Memory Flashcards
a hardware device used to store computer programs, instructions, and data (17 cards)
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
○ All DIMM are 64 bit.
SODIMM (Small Outline DIMM)
Smaller version of DIMM used in laptops, compact
desktops, and other small form factor systems.
○ Usually, <= 204 pins
○ Data and programs stored on the hard drive are loaded into RAM.
○ 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.
DRAM (dynamic random-access memory)
stores bits of data in capacitors that need to be continuously refreshed, hence
‘dynamic’ (capacitors leak)
○ SDRAM (synchronous DRAM)
■ Runs in sync with the system clock.
■ Faster than DRAM
○ ADRAM (asynchronous DRAM)
■ Operates asynchronously from the clock cycle.
■ Slower than SDRAM
Virtual RAM
Process of transferring data from RAM to disk storage
★ Referred to as a “paging file” on Windows and “Swap Space” on Mac/Linux
Virtual RAM, also known as virtual memory, is a system that allows your computer to use hard drive or SSD space as extra memory when it runs out of physical RAM.
It’s not real RAM, but it helps your system stay functional during heavy multitasking or when your programs need more memory than you physically have.
Virtual RAM Types
FPM DRAM (fast page mode DRAM)
EDO DRAM (extended data out DRAM)
BEDO DRAM (burst EDO DRAM)
SDR SDRAM (single data rate SDRAM)
DDR SDRAM
Doubles the speed of RAM by sending data on the rising and falling edge of the clock
signal (clock signals are timed electrical pulses)
○ 184 pins
○ 2X faster than SDRAM
DDR2 SDRAM
Faster and more power efficient than DDR
○ 240 pins
DDR3 SDRAM
Twice as fast as DDR2 and uses even less power.
○ 240 pins
○ Notches to attach to motherboard are in different places.
DDR4 SDRAM
288 pins, higher speeds
○ Uses less power.
DDR5 SDRAM
Doubles the speed of DDR4 to 6.4 Gbps
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
SRAM (static random-access memory)
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
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 its own CPU core.
Level 2 cache
■ 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 cache
■ 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
ECC
code that checks that data was processed correctly and makes any needed corrections.
ROM (read-only memory)
It’s a type of non-volatile memory, which means it keeps its data even when the power is turned off.
As the name suggests, ROM is mostly readable, not writeable.
It contains pre-programmed instructions that do not change.
ROM is used to store essential instructions that your computer needs to start up and operate properly — usually the firmware or BIOS.
