VRAM

VRAM

     

•  Video RAM

•  Used by PC’s graphics card

•   Dual Ported
•  20% faster than DRAM but more expensive
•   Affects number of colours and resolution displayed by monitor

WRAM

•   Another type of Video RAM
•   Also dual ported
•   Faster than VRAM

Adding RAM

• Major factor in system speed
• Excessive hard drive activity (watch HDD LED)
• Disk thrashing
• Launch Task Manager (CTRL-ALT-DEL once)
• Swop file = page file
• Determine current RAM (Windows – pause/break)
• Wear an anti-static wrist strap
• DIMMs – push down until both clips are home
• SIMMs – 45 degrees then push back

DDR SDRAM

•    Double Data Rate synchronous dynamic RAM

•    Processor can read/write from DDR SDRAM on both the up and down cycle of the clock

•     Works with Athlon and later AMD processors double-pumped FSB

•   Runs at 200, 266, 333 or 400 MHz

•   184-pin DIMMs

•   Maximum transfer rate to L2 cache is 1064 MBps

•      Intel has given in and now supports DDR SDRAM!

           DDR2 SDRAM

•   Runs cooler and uses less power than DDR

         240 pin

         RDRAM

•  Rambus Dynamic RAM

          uses a Rambus in-line memory module (RIMM)

•   Developed by Intel for the Pentium 4

•  184-pin, 160-pin SO-RIMM for laptops

•   Can’t install a RIMM in a DIMM slot and vice-versa

           RIMMs generate a lot of heat

•    Maximum transfer rate to L2 cache is 1600 MBps

           Hasn’t been adopted by motherboard manufacturers yet

•   RIMMs must be installed in pairs – CRIMM in unused slot

SDRAM

•           Synchronous Dynamic Random Access Memory

•          Tecnically correct name is SDR SDRAM

•          4 to 6 times faster than FPM and EDO RAM

•          Linked to the system clock on motherboard (Unlike FPM and EDO) – resulting in less time wasted by the processor waiting for data

•          (66, 75, 83, 100, 133) Mhz are the common SDRAM speeds

•          N.B. SDRAM speed must be equal to or faster than the motherboard speed

•          168-pin DIMMs

•          PC100/133 standards

•          Maximum transfer rate to L2 cache is 528 MBps

•           

Double Pumping

•          First used with AMD Athlon processor

•           Enabled the Athlon to send/receive two bits of data with every clock cycle to/from the Northbridge

•           Effectively doubles the system bus speed (motherboard speed)

•           Athlons with 100 Mhz or 133Mhz FSBs between the Northbridge and the CPU ran at 200Mhz or 266Mhz

•           Double Pumping systems use DDR SDRAM

        Double Pumping

•          First used with AMD Athlon processor

•           Enabled the Athlon to send/receive two bits of data with every clock cycle to/from the Northbridge

•           Effectively doubles the system bus speed (motherboard speed)

•           Athlons with 100 Mhz or 133Mhz FSBs between the Northbridge and the CPU ran at 200Mhz or 266Mhz

•           Double Pumping systems use DDR SDRAM

DRAM Types

•          FPM RAM

•          EDO RAM

•          SDRAM

•          DDR SDRAM

•          RDRAM

•          VRAM

•          WRAM

      FPM RAM

•          Fast Page Mode Random Access Memory

•          Access speed = time taken for FPM chip to supply Northbridge with data – measured in nanoseconds

•          60ns is faster than 100ns

EDO RAM

•          Extended Data Out Random Access Memory

•          Early 1990’s – used with some 486’s and with Pentiums

•          Came in 72-pin SIMM or 168-pin DIMM

•          Needed special Northbridge design

•          Needed less refreshing than FPM RAM so data was available to the processor more often

•          Maximum transfer rate to L2 cache is 264 MBps.

•          Used throughout the 1990’s

Eventually replaced by SDRAM

RAM DIMM

•          Dual In Line Memory Module

•          All DIMMs are 64 bit

•          168-pin used for DRAM and SDRAM

•          184-pin used for DDR RAM

•          Send/receive 64 bits of data

•          Capacity of 8Mb to 1Gb per module

•          ECC

•          A DIMM can be single or double sided

      

            RAM SODIMM

•          Small Outline Dual In Line Memory Module

•          144 pin

•          Used in laptops

•          Physically smaller than standard DIMMs

            RAM RIMM

•          Rambus inline memory module (aka RDRAM)

•          Used only in Pentium 4 systems

•          Uses heat spreader

•          184-pin RIMM for desktops

•          160-pin SORIMM for laptops

•          RIMMs must be installed in pairs

•          Continuity RIMMs (CRIMMs) installed in unused slots

RAM SIMM

•          Single In-Line Memory Module

•          FPM (Fast Page Mode) DRAM

•          30 or 72 pin connector

•          30-pin SIMM could send/receive 8 bits of data

•          Parity checking

•          Installed in pairs due to 16 bit memory bus of the 80286 processors

•          72-pin SIMM could send/receive 32 bits of data

•          80386 and 80486 processors had a 32 bit memory bus and used 72 pin SIMMs allowing up to 256Mb RAM

•          A SIMM can be single or double sided

DIPP

•          Dual Inline Pin Package

•          Connected directly to the motherboard

•          Took up a lot of space on the motherboard

•          Replaced by SIPPs

       

                     SIPP

•          Single Inline Pin Package

•          Eliminated need for individually installing memory modules

•          30 pins but easy to break

•          Very quickly replaced by 30-pin SIMMs

RAM Modules

•          RAM memory chips are sold in modules.

•          7 module types

•          DIPP

              SIPP

•          SIMM

•          DIMM

•          DIMM

•          DIMM

•          SORIMM

Types of RAM - SRAM

•          Static RAM

•          Uses transistors to store data and doesn’t need to be refreshed

•          SRAM is used for L1 and L2 cache memory

•          Physically bigger (x10) than DRAM

          

                      Types of RAM - DRAM

•            Dynamic RAM (DRAM)

•          Uses a series of tiny capacitors to store data, which need to be refreshed regularly

•          ¼ the speed of SRAM

•          Needs to be constantly refreshed

Data is not available to the processor while the RAM

Measuring RAM

•          Made up of individual bits which are 1’s or 0’s (5v or 0v)

•          8 bits = 1 byte

•          A byte represents a character, number or symbol

•          1024 bytes = a kilobyte

•          1024 kilobytes = a megabyte

•          1024 megabytes = a gigabyte

Development of RAM

•          8088 – 1Mb of RAM

•          286 – 4Mb of RAM

•          486 - 16Mb of RAM

•          Pentium - 32Mb of RAM

•          Pentium II - 64Mb of RAM

•          Pentium IV or Athlon – 128Mb to 4Gb RAM

Athlon 64 – potentially 172,000,000 Gb RAM!!!