IS 148 A Certification, Hardware

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IS 148 A Certification, Hardware

• Chapter 3
• Random Access Memory

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Introduction Chapter 3 RAM

• In this chapter we will learn
• How to identify types of RAM
• How to handle RAM safely
• To install RAM correctly
• What to look for when you expect Ram Errors
• Steps to correct RAM errors

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RAM Overview

• Today RAM memory chips are soldered onto a
  special removable circuit board that fit into a
  socket on the MB. They are often referred to as
  memory sticks.
• RAM is currently being provided in two basic form
  factors or packages
• Dual Inline Memory Modules DIMM
• SDRAM
• DDR SDRAM
• Rambus Inline Memory Modules RIMM
• RIMM is actually not a type of memory but names
  the manufacturer of the produce.
• The RIMM form factor is more accurately called
  Rambus Dynamic RAM.
  

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From SIMMS to DIMMS

• SIMMs (single in-line memory modules) evolved
  into DIMMs (dual in-line memory modules)
• DIMMs doubled the number of paths between the
  module and motherboard by using each side of the
  edge connector independently.
• SIMMs are generally used in pairs, whereas DIMMs
  may be used one at a time.
• Rambus modules must be used in pairs or with a
  blank spacer.
  

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Possible Memory ModulePackaging for ATX
Motherboards and Laptops
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SO DIMMS for Laptops
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R AM Types

• RAM is divided into two major types
• DRAM Dynamic RAM
• SRAM - Static RAM
  

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Dynamic RAM

• The most common type of computer memory, also
  known as D-RAM or DRAM.
• It usually uses one transistor and a capacitor to
  represent a bit.
• The capacitors must be energized hundreds of
  times per second in order to maintain the
  charges.
• Unlike firmware chips both major varieties of RAM
  (dynamic and static) lose their content when the
  power is turned off.

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DRAM Characteristics

• Less expensive than SRAM
• Slower than SRAM
• Must be refreshed to hold the data
• Most of the memory on a motherboard is DRAM
• Uses a transistor and a capacitor circuit to
  represent a bit.
• The capacitors must be energized hundreds of
  times per second in order to maintain the
  information.
  

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SRAM Characteristics

• SRAM is faster than DRAM.
• More expensive to manufacture and purchase
• Uses digital Flip-Flop circuits to store data .
• SRAM does not require refreshing to maintain the
  stored data.
• SRAM is 4 times faster than DRAM .
• SRAM is used for CACHE memory.

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Classifications of RAM

• EDO Extended Data Out
• SDRAM Synchronous Dynamic RAM
• DDR SDRAM Double Data Rate SDRAM
• RDRAM Rambus DRAM
• VRAM Video RAM
• WRAM Window RAM

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Extended Data Out (EDO RAM)

• EDO (extended data output) RAM is a type of RAM
  chip that improves the time to read from memory
  on faster microprocessor chips.
• EDO RAM was initially optimized for the 66 MHz
  Pentium. For faster computers, different types of
  synchronous dynamic RAM (SDRAM) are recommended.
  

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SDRAM (synchronous dynamic RAM)

• Current RAM for most of todays systems
• Delivers data in high speed bursts
• Runs at the speed of the system bus
• Rated according to the highest speed bus it will
  run on. 66,100 or 133 MHz.
• Most common form of SDRAM is 168-pin DIMMs
• For laptops there are two small outline forms of
  72 and 144 pin.

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DDR SDRAM

• Newer AMD and most Pentium mother boards support
  DDR SDRAM
• These memory sticks actually complete two
  instructions per clock cycle, effectively
  doubling the speed of the memory operations
• Packaged in either 184 pin DIMM for desktops and
  either 200 or 172 pin small outline for laptops.
• Bus speeds range up to 533 mega-transfers per
  second off of a 233 MHz bus.
• These memory sticks may also be sold using a
  Module Standard number like PC3200 which
  corresponds to a speed of 433 mega-transfers per
  second
  

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DDR2 SDRAM

• A new and faster version of DDR memory which
  became available in early 2004 with bus speeds
  starting at 400 MHz and ranging up to 800 MHz.
• Transfer rates up to 6,400 MBps.

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2004 price comparisons

• A 512 MB single stick of
• Feb. Sept
• SDRAM 116.52 44.00
• DDR SDRAM 92.80 103.50
• RDRAM 103.50 99.88
• DDR2SDR N/A 177.10
  

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Dual Memory Channel Access

• High end motherboards may have dual memory
  channel access that effectively doubles the speed
  of DDR SDRAM.

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RDRAM

• Developed by Rambus, Inc.
• Have transfer rates up to 800 MHz.
• If dual memory access channels are used the
  transfer speeds may be as high as 1.6 GHz.
• Rambus can only be used on machines that use
  Northbridge chips sets that support RAMBUS memory
  

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VRAM

• Used on video cards
• Very fast type of DRAM
• VRAM is dual ported meaning it can be read from
  and written to at the same time.
• Dual porting allows the CPU and the video card on
  board video processor to access the memory at the
  same time.

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WRAM

• Window RAM (WRAM), unrelated to Microsoft
  Windows, is very high-performance video RAM that
  is dual-ported and has about 25 more bandwidth
  than VRAM but costs less.
• It has features that make it more efficient to
  read data for use in block fills and text
  drawing.
• It can be used for very high resolution (such as
  1600 by 1200 pixels) projection using true color.
• It's used in the Matrox Millenium video card.
  

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Figuring the amount of memory that can be
addressed

• The amount of memory that can be addressed is
  determined by 2X power where X is the number of
  address lines.
• 216 65,536 bytes of addressable memory.
• 220 1,048,576 1Megabyte of addressable memory
  
• 232 4,294,967,296 bytes or 4GB of RAM
  

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Memory Banks

• Memory banks on the MB usually consisted of two
  memory sockets
• When memory banks were present both sockets had
  to be filled. It was also advisable that the
  memory sticks be
• from the same manufacturer
• Of the same type and speed

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Memory banks 168 pin DIMMS

• Motherboards using 168 pin SDRAM did not use
  memory banks and memory sticks could be added one
  at a time.
• The exception to this would be motherboards using
  dual channel DDR SDRAM.
  

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Rambus Memory Stick Rules

• Pentium 4 motherboards that use RDRAM do require
  that no socket be left empty.
• A card referred to as a terminator or continuity
  RIMM stick is required to fill any unused socket
  

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Handling RAM

• RAM is very sensitive to ESD
• Always store and transport in antistatic bags
• Handle by the edges and avoid touching the metal
  contacts at the bottom of the memory stick
• Avoid touching the leads on the PC card

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Installing RAM modules

• Turn off and unplug the computer
• Use ESD precautions
• DIMM and RIMM go into the socket vertically
• There are guide notches on the memory sticks and
  bridges in the sockets so the DIMM can only be
  inserted facing the correct direction

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RAM retention clips

• Before inserting a memory stick in to a socket be
  sure that the white RAM retention clips, on
  either end of the socket, are open.
• Place the DIMM in the socket vertically and apply
  pressure on each end of the DIMM with your
  thumbs.
• In new sockets it may be necessary to rock the
  DIMMS into the socket.

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Removing a DIMM or RIMM

• To remove a memory stick push the retention clips
  down with your index fingers.
• The memory stick will be released from the
  socket.
• Be careful when removing memory as the memory
  sticks will actually pop up out of the sockets.
  

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Confirm RAM Installation Windows
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Confirm RAM from DOS
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Troubleshooting RAM errors

• Indications from the PC that a RAM error has
  occurred can actually be an error that has
  nothing to do with RAM
• You must determine if the error is false or
  genuine.

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False Memory Errors

• An Out of Memory Error is more likely is an
  indication that the system resources are low.
• The following errors
• Page Faults
• Exception Errors
• Blue Screen of Death
• are most likely related to
• badly fragmented hard drives,
• CPUs running at near maximum capacity
• Heat or dying power supplies
  

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Common Symptoms of RAM Errors

• Common start up errors include
• System will not boot repeating beep code
• System boots but no video display
• System boots but misreports RAM size
• System boots but reports a memory or address
  error.
• The majority of genuine memory error occur after
  making changes to hardware.

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Common Causes of RAM Errors

• RAM configuration errors Installing the wrong
  type or speed RAM, banking or termination rule
  errors
• Improper Installation RAM sticks not seated,
  corrosion, disturbing other setting during
  installation
• Faulty RAM Damaged by ESD or bad from the
  factory.

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Questions