Overview and Introduction

1
Overview and Introduction

• Large desktop PCs have connectors and space
  inside for extras
• Slimline PCs, laptops and PDAs often accept
  miniaturised, specialised add-ons
• Most computers accept external extensions,
  usually connected through the USB ports
• Soon external devices will be connected using
  no cables at all!

2
Extending your PC

• The ability to add extra capabilities to a
  computer is very useful
• Some computers have extremely limited expansion
  capability, or none at all
• Most PCs have internal expansion slots (the PCI
  or PCIe buses) for adding extra devices
• Look at the back of a PC and you can see the ends
  of the various plug-in cards

3
Graphics

• Most PCs have a separate graphics adapter
• Graphics cards support at least 256 colours (1
  byte)
• Also may support64K colours (2 bytes),16.7M
  colours (3 bytes),16.7M plus an extra
  transparency channel (4 bytes)

4
Graphics

• 2D graphics cards tend to use between 1MB and 4MB
  of RAM for the screen
• 800 x 600 pixels gt 1,440,000 bytes
• 1024 x 768 pixels gt 2,359,296 bytes
• 1280 x 1024 pixels gt 3,932,160 bytes
• Values calculated assuming 3 bytes per pixel
  (24-bit colour, 16.7M colours)

5
3D-Graphics

• Combined 2D and 3D graphics adapters are popular
  at the moment
• 3D graphics are mostly used for games
• 3D graphics uses a lot more memory than 2D 64MB
  at least, up to 512MB (2005)

6
Sound

• Sound cards come in many forms the market spans
  simple business output, gaming and serious music
  making
• Most sound cards can record and play back sound
  at CD quality or better
• Many sound cards have two different types of
  sound-synthesis
• Wave-table, based on pre-recorded samples
• Fully synthetic, based on old Yamaha organ chips

7
SCSI

• SCSI cards come in many shapes and sizes
• Pictured here is a tiny 8-bit SCSI-1 card
  supplied as part of a scanner package
• SCSI-1 is a very old standard - SCSI-2 is more
  up-to-date and faster but has many variations
• Speed up to 80Mbytes per second

8
Networking

• In these days of Internet connectivity,
  computer-to-computer communication devices have
  become common
• Network cards broadly fall into two classes -
  fast and slow!
• Networking has dropped in price and complexity
  very rapidly

9
Modem

• The word modem stands for modulator/demodulato
  r
• The modem is a device which converts digital
  information into sounds when modulating...
• and converts sounds to digital information when
  demodulating
• This allows computers to use the phone lines like
  a cheap, slow network

10
Video Capture and Playback

• Video movie digitisation (recording to a PC) is
  often done using a separate add-in card
• Some 2D/3D graphics cards also have moderate
  video grabbing capability
• Video playback sounds like a job for a 2D
  graphics card - but sometimes they need help
• Modern graphics cards sometimes have some movie
  acceleration, particularly for DVD and video
  conferencing

11
Summary

• Adding new hardware to a computer is reasonably
  easy to do but adding the software to use the
  new hardware can be trickier
• External connections like USB make it easier
• Modems, network adapters and sound i/o can all be
  done through USB
• Graphics cards need to be very close to the heart
  of the computer still need to be internal