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CP1610: Introduction to Computer Components. Primary Memory. What is Memory?. Memory is used to: Store data; Store commands (instructions); Store system settings;. Computer Memory. Three categories of memory devices: Primary Memory; Secondary Memory; Archival Storage Devices;. - PowerPoint PPT Presentation
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CP1610:Introduction to Computer Components
Primary Memory
What is Memory?
Memory is used to:Store data;Store commands (instructions);Store system settings;
Computer Memory
Three categories of memory devices:Primary Memory;Secondary Memory;Archival Storage Devices;
What is Primary Memory?
Also called system memory. Essential for computer to operate. Stores data and commands to be used by the
CPU. Stores basic system settings. Two main types:
RAM ROM
RAM vs. ROM
RAM Random Access
Memory Stores data and
instructions Volatile
Examples: RAM chips CMOS
ROM Read Only Memory Stores basic system
settings Non-volatile
Example: BIOS
The Primary Memory Hierarchy
Notes in your locker, car, or at home, are too far away!
Retrieving Data from Secondary Storage
RAM: The book on your desk is much closer!
Cache: The papers in your hand are the next ones you will use!
RAM on the Motherboard
Static RAM (SRAM) Very fast; Expensive; Does not need to be
refreshed; Used as Cache; On Chip, Coast Card,
or inside CPU;
Dynamic RAM (DRAM) Slow; Cheaper; Needs constant
refreshing; Used as RAM; SIMMs, DIMMs and
RIMMs
Different Types of DRAM
SIMMSingle Inline Memory Module
DIMMDual Inline Memory Module
RIMMRambus Inline Memory Module
Installing a SIMM Chip
Installing a DIMM Chip
Installing a RIMM Chip
Older Types of RAM
Conventional RAM Fast Page Memory (FPM) Extended Data Out (EDO) RAM Burst EDO (BEDO) RAM
Newer Types of RAM
Sychronous DRAM (SDRAM) Synced with system clock
Double Data Rate (DDR) SDRAM Most popular today 184-pin DIMMs 200-pin SODIMMs
Rambus DRAM (RDRAM) Not as common Faster system bus RIMMs
Cache Memory Very fast SRAM Used to store the very next command or
data needed by the CPU Three Types:
L1L2L3
Error Correction Method used to:
Detect integrity of data stored in RAMEnsure memory is completePrevent data corruption or loss
Non-Error Correcting Memory:Used in older systems to speed up memory;
Types of Error Correction
Parity:Older;Cannot correct data corruption;
Error Correcting Code (ECC):Newer;Most widely used;Can correct data corruption;
How Parity Works
System Memory
Conventional Memory: First 1 MB of memory; Used to run programs and store system drivers;
High Memory (Hi-Mem): About 64 KB of memory just above the 1 MB point;
Extended and Expanded Memory: Anything above 1 MB; Systems must run in ‘Protected Mode’ to use;
Available to the user for any software
Reserved for device drivers and system functions
Anything above 1 MB