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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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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 ratingsMemory 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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Packaging
Individual chips Package
Memory chips Connecting wires Support chips Pins or edge contacts
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Individual chips
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Package typesPackage 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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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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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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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