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Memory systems

Unit objectives Describe the function of memory and

differentiate between different types of memory chips

Differentiate between different memory packages

Test memory with a memory testing application and troubleshoot memory problems

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Topic A

Topic A: Memory Topic B: Memory packaging Topic C: Memory troubleshooting

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Memory

RAM = Random Access Memory Working area for data during

processing Having sufficient RAM is critical

– Performance– Software support

Quality RAM is critical

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Measurement units

Bit Nibble = 4 bits Byte = 8 bits Word = based on CPU

– Pentium 4: 32-bit processor : 32 bit word

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Larger 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 or 1,099,511,627,776

bytes

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Memory types

Classify memory as:– Volatile vs. non-volatile– Static vs. dynamic– Asynchronous vs. synchronous

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Volatile vs. non-volatile memory

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

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Dynamic vs. static memory

Dynamic (DRAM)– Must be continually refreshed– Inexpensive– Small

Static (SRAM)– Refreshing not required– More expensive– Larger– Faster

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Asynchronous and synchronous

Asynchronous– Not synchronized to system clock– Consistent time to access and read data

Synchronous– Synchronized to system clock– Access data and return in one or more

clock cycles

SDRAM faster than ADRAM

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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

DDR Double Data Rate Double transfer rate of SDRAM with two transfers per clock cycle

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

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Access time

Latency Memory speed

– Nanoseconds vs. megahertz

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

Bandwidth

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Speed ratings

Memory type Technology Bandwidth Speed

PC100 SDRAM 0.8 GB/second 100 MHz

PC133 SDRAM 1 GB/sec. 133 MHz

PC1600 DDR 1.6 GB/sec. 100 MHz

PC2100 DDR 2.1 GB/sec. 133 MHz

PC2700 DDR 2.7 GB/sec. 166 MHz

PC3200 DDR 3.2 GB/sec. 200 MHz

PC2-3200 DDR2 3.2 GB/sec. 200 MHz

PC2-4200 DDR2 4.2 GB/sec. 266 MHz

PC2-5300 DDR2 5.3 GB/sec. 333 MHz

PC2-6400 DDR2 6.4 GB/sec. 400 MHz

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Activity A-1

Identifying memory characteristics

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Topic B

Topic A: Memory Topic B: Memory packaging Topic C: Memory troubleshooting

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Packaging

Individual chips Package

– Memory chips– Connecting wires– Support chips– Pins or edge contacts

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Individual chips

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SIMM

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Package types

Package Pins Used in

SIMM 30 386-class desktops, early Macintosh computers

SIMM 72 486 and early Pentium desktops

DIMM 100 Printers

DIMM 168 Pentium and Athlon systems

DIMM 184 DDR SDRAM in desktops

DIMM 240 DDR2 SDRAM in desktops

MICRODIMM 144 Sub-notebook computers

SODIMM 144 Laptop and notebook computers

SODIMM 200 DDR memory for laptops and notebooks

SODIMM 200 DDR2 memory for laptops and notebooks

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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

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Parity

9 chips,supportsparity

8 chips,no parity

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Activity B-1

Comparing RAM packaging

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Topic C

Topic A: Memory Topic B: Memory packaging Topic C: Memory troubleshooting

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Task Manager

Windows GUI utility Provides information on currently

running processes Version available on all Windows

operating systems– Windows 9x/Me Program List – Windows NT/2000/XP Task Manager

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Performance tab indicators

CPU Usage CPU Usage History PF Usage Page File Usage History Totals Physical Memory (K) Commit Charge (K) Kernel Memory (K) Summary data

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The Performance tab

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Activity C-1

Monitoring memory usage

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Activity C-2

Adjusting the Windows page file size

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Memory symptoms

201 BIOS error code at boot time Parity error message Computer randomly freezes 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

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Activity C-3

Troubleshooting memory

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Unit summary

Described the function of memory and differentiated between different types of memory chips

Differentiated between different memory packages

Tested memory with a memory testing application and resolved memory problems