Memory systems

Unit objectives Describe the function of memory and

differentiate between different types of memory chips

Differentiate between different memory packages

Install RAM Monitor memory usage Test memory and 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 Megabyte (MB) = 1024 KB = 1,048,576 bytes Gigabyte (GB) = 1024 MB = 1,073,741,824 bytes Terabyte (TB) = 1024 GB = 1,099,511,627,776

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– Small

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

ADRAM Asynchronous DRAM Not synchronized to the system clock

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 Double Data Rate Double transfer rate of SDRAM

with two transfers per clock cycle

DDR2 Double Data Rate 2 64 bits per transfer to double DDR performance

DDR3 Double Data Rate 3 Transfers data at a rate of 800–1600 MHz

Access time

Latency Memory speed

– Nanoseconds vs. megahertz

Overall speed– Doesn’t include latency– Doesn’t consider bus speed

Bandwidth

Speed ratingsMemory type Technology Bandwidth I/O bus clock speed Memory clock speed

PC100 SDRAM 0.8 GB/sec. 100 MHz 100 MHz

PC133 SDRAM 1 GB/sec. 133 MHz 133 MHz

PC1600 DDR-200 1.6 GB/sec. 100 MHz 100 MHz

PC2100 DDR-266 2.1 GB/sec. 133 MHz 133 MHz

PC2700 DDR-333 2.7 GB/sec. 166 MHz 166 MHz

PC3200 DDR-400 3.2 GB/sec. 200 MHz 200 MHz

PC2-3200 DDR2-400 3.2 GB/sec. 200 MHz 100 MHz

PC2-4200 DDR2-533 4.2 GB/sec. 266 MHz 133 MHz

PC2-5300 DDR2-667 5.3 GB/sec. 333 MHz 166 MHz

PC2-6400 DDR2-800 6.4 GB/sec. 400 MHz 200 MHz

PC2-8500 DDR2-1066 8.5 GB/sec. 533 MHz 266 MHz

PC3-6400 DDR3-800 6.4 GB/sec. 400 MHz 100 MHz

PC3-8500 DDR3-1066 8.5 GB/sec. 533 MHz 133 MHz

PC3-10600 DDR3-1333 10.6 GB/sec. 667 MHz 166 MHz

PC3-12800 DDR3-1600 12.8 GB/sec. 800 MHz 200 MHz

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 chips No more than 1 MB of memory

continued

Packaging, continued

Package– Small circuit board– Also 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 DRAM chips no longer corresponds to data being stored

Package types: desktops

SIMM 30-pin SIMM 72-pin DIMM 100-pin DIMM 168-pin DIMM 184-pin DIMM 240-pin

– DDR2– DDR3

RIMM 184-pin

Package types: laptops

MICRODIMM 144-pin SODIMM 144-pin SODIMM 200-pin

– DDR– DDR2

SODIMM 204-pin

Memory error recovery

Parity — Detects an error 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 Ground yourself to computer’s chassis Move around as little as possible Lay module in static-safe packaging

atop the computer’s power supply to safely discharge potential differences

Always handle modules by their edges Never touch chips or contacts

Inserting memory modules

1. Insert module at 45-degree angle

2. While pushing into slot, move module to fully vertical or horizontal position Clips should engage automatically

when module is fully seated

Removing a module

1. Gently release the retaining clips at both ends of the module

2. Move the module to a 45-degree angle

3. Remove the module

Storage

Store in:– Original packaging– Static-safe bag

Static-safe bag– Metal-coated plastic – Conductive – Transmits static charges slowly

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 Users less power; generates less heat Not all RAM is available to OS and

applications 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

Others use memory cards similar to those in digital cameras

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) PF Usage (XP/2000) Physical Memory Usage History

(7/Vista) 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

On boot partition by default Determined by amount of RAM Size automatically increases or

decreases for best performance Can manually override the settings Page file size:

– RAM × 1.5 – System’s peak commit value

Can move file to different hard disk

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– DocMemory Diagnostic — Free,

unsupported

Boot from floppy or CD Full test suite can take many hours

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 General Protection

Fault, 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 between different types of memory chips

Differentiated between different memory packages

Installed RAM into a system while handling it properly and meeting your PC’s installation requirements

Monitored memory usage Identified and resolved memory

problems