Memory systems
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Transcript of Memory systems
Memory systems
Unit objectives: Describe the function of memory and
differentiate among various types of memory chips
Differentiate among the various memory packages
Install RAM into a system while handling it properly and meeting your PC’s installation requirements
Monitor memory usage Troubleshoot memory problems
Topic A
Topic A: Memory Topic B: Memory packaging Topic C: Memory installation Topic D: Memory monitoring Topic E: Memory troubleshooting
Memory
RAM: random access memory Working area for data during
processing Need sufficient RAM for
– Performance– Software support
Quality of RAM is important
Measuring memory
Cells– Store a single bit of data– 0 or 1– Represents on/off or yes/no
Measurement units – Bit– Nibble = 4 bits– Byte = 8 bits– Word = based on CPU
32-bit processor: 32-bit word 64-bit processor: 64-bit word
Larger memory units Byte (B) = 8 bits Kilobyte (KB) = 1024 bytes = 210 bytes Megabyte (MB) = 1024 KB = 220 bytes Gigabyte (GB) = 1024 MB = 230 bytes Terabyte (TB) = 1024 GB = 240 bytes
Memory types
Classify memory as:– Volatile vs. non-volatile– Static vs. dynamic– Asynchronous vs. synchronous
Volatile vs. non-volatile memory
Volatile: Loses contents without power Non-volatile: Keeps contents without power
RAM Volatile Random access memory
CMOS Volatile Complementary metal oxide semiconductor
ROM Non-volatile Read-only memory
PROM Non-volatile Programmable read-only memory
EPROM Non-volatile Erasable programmable read-only memory
EEPROM Non-volatile Electronically erasable programmable read-only memory
Flash Non-volatile
Dynamic vs. static memory
Dynamic (DRAM)– Must be continually refreshed– Inexpensive– Physically small chips
Static (SRAM)– Refreshing not required– More expensive– Larger– Faster
Typical uses– Main system memory: DRAM– Cache memory and CMOS: SRAM
Asynchronous vs. synchronous
Asynchronous– Not synchronized to system clock– Consistent time to access and read data
Synchronous– Synchronized to system clock– Accesses data and returns in one or
more clock cycles
SDRAM faster than ADRAM
Memory access typesDRAM Dynamic RAM Older technology
FPM Fast Page Mode Improved over DRAM
VRAM Video RAM Dual port, optimized for video
EDO Extended Data Out Improved over FPM
BEDO Burst Extended Data Out Adds pipelining to EDO
SDR SDRAM
Synchronous DRAM Interleaving permits overlapped requests
DRDRAM Direct Rambus DRAM 16-bit memory bus and two transfers per clock cycle
continued
Memory access types, continuedDDR SDRAM
Double Data Rate Double transfer rate of SDR SDRAM with two transfers per clock cycle
DDR2 SDRAM
Double Data Rate 2 Double transfer rate of DDR SDRAM with four transfers per clock cycle
DDR3 SDRAM
Double Data Rate 3 Double transfer rate of DDR2 SDRAM with eight transfers per clock cycle
Access time
Latency Memory speed
– Nanoseconds vs. megahertz
Overall speed– Doesn’t include latency
Bandwidth
Speed ratings
Activity A-1
Identifying memory characteristics
Topic B
Topic A: Memory Topic B: Memory packaging Topic C: Memory installation Topic D: Memory monitoring Topic E: Memory troubleshooting
Packaging Early PCs used individual DRAM chips
continued
Packaging, continued
Package– Small circuit board– More commonly called a module– Installed in slot
Module contains– Memory chips– Connecting wires– Support chips– Pins or edge contacts
Single- and double-sided modules
Early DRAM had chips on just one side
Double memory by placing chips on both sides
Double-sided modules have two rows of pins at bottom– Pins on front aren’t connected to pins on
back
Number of chips no longer has a 1:1 chip-to-bit limit
Package types
SIMM 30-pin – ADRAM
SIMM 72-pin – ADRAM
DIMM 168-pin – SDR SDRAM
DIMM 184-pin – DDR SDRAM
DIMM 240-pin – DDR2– DDR3
RIMM– 184-pin – 16-bit– 232-pin – 32--bit
continued
Package types, continued
MicroDIMM 144-pin SODIMM 144-pin – SDR SDRAM
SODIMM 200-pin– DDR– DDR2
SODIMM 204-pin – DDR3 SDRAM
Modules and chips
PC100 and PC133 use SDRAM PC1600, PC2100, PC2700, and
PC3200 use DDR SDRAM PC2-3200, PC2-4200, PC2-5300,
PC2-6400, and PC28500 use DDR2 SDRAM
PC3-6400, PC3-8500, PC3-10600, and PC3-12800 use DDR3 SDRAM
Memory error recovery
Parity — Detects an error– Even– Odd– Mark– Space
ECC — Detects and corrects an error Desktop memory — No parity or ECC Server memory — Often includes
parity or ECC
Parity
9 chips,supportsparity
8 chips,no parity
Activity B-1
Comparing RAM packaging
Topic C
Topic A: Memory Topic B: Memory packaging Topic C: Memory installation Topic D: Memory monitoring Topic E: Memory troubleshooting
Memory installation considerations
Banking requirements Proper handling techniques Slot insertion techniques Safe storage BIOS configuration
Banking requirements
Install memory in groups called banks Bank might include 1, 2, or 4 slots Must fill every slot in a bank Might have to use same type and
speed of memory in every slot Leave extra banks empty
– With DRDRAM, install continuity modules
Dual-channel architecture
Proper handling
Unplug computer before opening it Dissipate static Move around as little as possible Always handle modules by their edges
Inserting memory modules
SIMM1. Insert module at 45-degree angle2. While pushing into slot, move module
to fully vertical or horizontal position. Clips should engage automatically when module is fully seated
DIMM1. Spread retaining clips before insertion2. Insert the module straight into the slot,
perpendicular to the motherboard3. Push firmly until the retaining clips
snap into place on either side
Removing a module
SIMM1. Gently release the retaining clips at
both ends of the module2. Move the module to a 45-degree angle
if it doesn’t do so automatically3. Remove the module
DIMM1. Release the retaining clips on both
ends of the module2. Remove the module by pulling it
straight up from the slot
CMOS configuration
BIOS checks memory at boot Compares actual memory with CMOS
entry Follow prompt to update CMOS entry
Activity C-1
Adding memory to a desktop computer
Notebook memory
Location varies from notebook to notebook
Refer to documentation Shut down notebook, unplug cord, and
remove battery
Shared video memory
Main system memory shared with video circuitry– No dedicated video memory
Reduces cost Uses less power; generates less heat Not all RAM is available to OS and
applications (does not show as present)
Slower than dedicated video memory Add more system memory to increase
performance
Activity C-2
Adding memory to a notebook computer
Memory in handheld computers
Expandable memory, a feature of more expensive handhelds
Some use modules similar to those in notebooks
Most use memory cards similar to those in digital cameras
Have a slot for inserting a flash memory card
Consult the manual
Activity C-3
Adding memory to a handheld computer
Topic D
Topic A: Memory Topic B: Memory packaging Topic C: Memory installation Topic D: Memory monitoring Topic E: Memory troubleshooting
Task Manager
Windows GUI utility Provides information on processes running Version available in all Windows OSs
– Windows 9x/Me Program List – Windows NT/2000/XP/Vista/7 Task Manager
Access:– Ctrl + Alt + Delete – Right-click empty space in the taskbar and
choose Task Manager – Ctrl + Shift + Esc
Performance tab indicators
CPU Usage CPU Usage History Memory (7/Vista) Physical Memory Usage History
(7/Vista) PF Usage (XP/2000) Page File Usage History (XP/ 2000)
continued
Performance tab indicators, continued
System (7/Vista) Totals (XP/2000) Physical Memory Commit Charge Kernel Memory Summary data
The Performance tab
Activity D-1
Monitoring memory usage
Virtual memory
Optimizing the page file
1. On boot partition by default
2. Determined by amount of RAM
3. Size automatically increases or decreases for best performance
4. Can manually override the settings
5. Page file size range:1. RAM × 1.5 to 3.0
2. System’s peak commit value
6. Can move file to different hard disk
Changing page file size
1. In Windows 7/Vista, click Start, right-click Computer, and choose PropertiesIn Windows 2000 /XP, right-click My Computer and choose Properties
2. In Windows 7/Vista, click Advanced system settingsIn Windows 2000/XP, activate the Advanced tab
3. In the Performance section, click Settings, and then activate the Advanced tab
4 In the Virtual memory section, click Change
5 Clear Automatically manage paging file size for all drives
6 Select Custom Size, and set the initial and maximum size
Activity D-2
Changing the size of the Windows page file
Topic E
Topic A: Memory Topic B: Memory packaging Topic C: Memory installation Topic D: Memory monitoring Topic E: Memory troubleshooting
Memory testing
POST not sufficient Use testing utility
– Memtest86 — Free, open source– Microsoft Windows Memory
Diagnostic — Free, unsupported
Boot from floppy or CD
Memory-related problems
201 BIOS error code at boot time Parity error message Computer randomly freezes (locks up)
or crashes Wrong amount of memory reported by
the BIOS Windows reports Page Fault or
Exception errors Random crashes, corrupted data,
strange application behavior
Activity E-1
Troubleshooting memory
Unit summary
Described the function of memory and differentiated among various types of memory chips
Differentiated among the various memory packages
Installed RAM into a system while handling it properly and meeting your PC’s installation requirements
Monitored memory usage Resolved memory problems