Understanding Memory Specifics

1
Understanding Memory Specifics

• Types and performance of RAM

2
How much is enough?

• Minimum to Boot 256MB
• Minimum Functional 512 MB
• Optimal 1GB
• Smooth Sailing gt 2GB

3
Are there different types?

• The type of memory matters to the performance of
  a system
• Two Basic Types
• DDR
• DDR2
• There are two older RDRAM and SDRAM modules but
  these are outdated and should be avoided in a new
  computer purchase

4
DDR-SDRAM (2000)

• Double Data Rate Synchronized Dynamic Random
  Access Memory
• Uses high bandwidth DRAM technology
• Works well with highly defined graphics

5
RAM (1970 Intel)

• A group of dynamic RAM chips
• It is the computers primary workspace
• RAM requires power to maintain its content

6
SIMMs

• Single In-Line Memory Modules
• First mass-produced Memory Packages

7
DIMMs

• Dual In-Line Memory Modules
• Used in Pentiums and PowerMacs

8
SODIMM

• Small Outline DIMM Modules
• Used by many brands of notebook computers
• 2 X 1 inch
• The Apple iMac desktop uses these instead of
  traditional DIMMs

9
Non-Parity vs. Parity

• As data moves through the computer, errors can
  occur
• By adding a single bit to each byte of data, this
  bit is responsible for checking the integrity of
  the other 8 bits while the byte is moved or
  stored
• This does not correct an error, it only notifies
  the user that one has occured

10
Non-Parity

• There is not extra parity checking bit
• Apple Computers and most Pentium class systems
  have no parity chips
• Why? Memory errors are rare and a single bit
  error will most likely be harmless.

11
EDO (1995)

• Extended Data Output
• Used in non-parity configurations in Pentium
  machines.
• EDO shorted the read cycle between main memory
  (RAM) and the microprocessor
• EDO chips allow the CPU to access Memory 10 to 20
  percent faster

12
SDRAM (1997)

• Synchronous DRAM
• It is the fastest DRAM technology (with the
  exception of DDR)
• It uses a clock to synchronize the signal input
  and output. The clock coordinates with the
  microprocessor clock so that both are in synch.

13
SRAM(1998)

• Static RAM
• Data stored in this type of memory does not
  require recharging to retain the data
• This data is much more expensive

14
Cache memory

• L1 Cache a very fast (SDRAM) type of memory
  that is built into the actual microprocessor
  chip. It stores frequently used instructions.
• L2 Cache memory external to the microprocessor.
  It is usually stored on a separate chip

15
RDRAM (1999)

• Rambus DRAM
• First used in gaming systems
• Used in multimedia and 3D graphics and has a high
  bandwidth
• RDRAM gives a 300 performance gain over using
  SDRAM