More Motherboard Jargon

1
More Motherboard Jargon!

• Covering various areas today
• Youve seen the adverts MMX, 3DNow!, SSE
  (versions 1,2,3,4)What on earth are they?
• RAM memory chips, temporary working storage
• CMOS RAM a memory chip for system settings
• PSU the power supply, surprisingly important
• ROM permanently fixed memory chips
• BIOS the Basic Input Output System (huh?)

2
TLA fever

• MMX was an enormously over-hyped technology
• 3DNow! and SSE all target the same area
• MMX is designed to allow simple operations to be
  applied to multiple pieces of data simultaneously
• Its a kind of simple SIMD system
• Single Instruction, Multiple Data
• c.f. MIMD, Multiple Instructions, Multiple Data

3
MMX stands for what exactly?

• Which would you choose?
• Mass Marketing eXercise
• Matrix Maths eXtensions
• Multi-Media eXtensions
• MMX-type instructions make a difference in
  operations common in
• media decoding (e.g. sound, video streams)
• image processing (e.g. photo processing, DVD
  playing)
• sound processing (e.g. speech recognition, sound
  f/x)

4
Memory RAM

• Random Access Memory isnt random at all, its
  just not serial memory
• RAM is the rapid, working, temporary memory of
  the computer (n.b. dont confuse with HD)

5
Memory RAM

• Current RAM types include
• DRAM, SDRAM
• DDR, DDR2
• RAMBUS RAM
• WRAM/WGRAM
• You need a specific type for a particular system

72-pin
168-pin
Cache
6
RAM packaging

• RAM comes in many formats, including
• 30-pin SIMM Very old!
• 72-pin SIMM old!
• 168-pin DIMM
• 184-pin DDR (just going, 2006)
• 240-pin DDR2 (new, 2005)
• DIL (classic chip shape)
• Flat, square high-density chips
• Speed information may bevisible on the packaging

7
RAM Performance

• One nanosecond (1ns) is one billionth of a second
• Main memory usually runs at 5ns or better (as
  slow as 60ns in very old systems)
• 5 nanoseconds cycle time means that data can be
  fetched 200 million times per second
• Fast RAM is more expensive, as you might expect

8
CMOS RAM

• The CMOS RAM is special memory (often a separate
  chip) that needs very little power to hold data
• Key system settings are kept in CMOS, e.g.
  hard-drive settings and various motherboard
  settings
• Most older PCs have 256 bytes of CMOS RAM
• Motherboards often have a jumper connection to
  clear it useful when completely reconfiguring a
  system

9
Power

• Motherboards use lots of 12v, 5v and 3v DC power
• How much power does a PC use?
• The answer depends on the number of add-in cards,
  internal and external devices
• Power supply units (PSUs) are usually rated at
  150 to 500 Watts (CPU can use 120W or more)
• Modern ATX PSUs support low power and software
  switching modes

10
Power play

• Does the amount of power a PC needs vary?
• CD-ROMs, DVDs and hard disc drives draw more
  power when spinning up for the first time
• 3D graphics accelerators draw more power in 3D
  mode than in 2D mode
• CD access plus 3D graphics mode change often
  happens when starting a game up
• If your computer needs more power than the PSU
  can supply, what happens?

11
ROM

• Read Only Memory can be read but not written to
• The computer needs some instructions when it
  starts up - these are in the BIOS ROM
• Modern BIOS ROMs are so-called flash ROM
• Flash ROMs are a form of EEPROMs firmware
• They allow BIOS updates without the need for
  physically swapping the ROMs
• But there can be safety security problems!

12
Summary

• We have discussed MMX-type instructions
• We have seen various types of RAM
• Including CMOS RAM for system settings
• We have discussed system stability and the power
  requirements of a PC
• The need for some built-in instructions has
  been briefly discussed