PC Architecture

• Memory - main
  • simms
    • edo --72 pin
    • fast page mode --32 & 72 pin
  • dimms (double sided simms) 72 & 168 pin
  • sdram 168 pin
    • 66 bus -- 10ns
    • 100 bus - 7ns
  • Bios tells Linux how much memory is in system. Most bios's only tell Linux that the there is only 64meg even though there may be more. We can fix this by telling lilo what the real amount is.
• cache
  • on chip cache
  • Some motherboards only cache a max of ?, If more memory is added then none of the memory is cached. This can thus make the system slow because none of the memory is cache Example is the Intel TX chipset only caches 64meg. Intel LX Pentium II boards only cache 512Meg. The spec said 1 gig but it does not work.
• CPU
  • Intel 386
  • Intel 486
  • Intel Pentium Pro
  • Intel Pentium & Pentium MMX
  • Intel Pentium II
  • AMD ( not supported at Fermi)
  • Cyrix ( not supported at Fermi)
• I/O bus
  • isa
  • eisa (support ?)
  • micro channel ( not supported at all by Linux)
  • vlb
  • pci
• Disk
  • mfm - old (relative)
  • ide
    • max of 2 devices per ide controller
      • one drive is jumpered as master
      • other is slave
    • normally 2 controllers on todays motherboards -- 0 & 1
    • /dev/hda - master drive on controller 0
    • /dev/hdb - slave drive on controller 0
    • /dev/hdc - master drive on controller 1
    • /dev/hdd - slave drive on controller 1
    • atapi
      • cdrom
      • zip
      • ls-120
      • cd-r
    • disk
      • <504 meg (bios)
        • Original pc
        • <= 1024 real cylinders
      • 504meg - 8.4gig (bios)
        • lba (logical block address)
        • <1024 cylinders by changing cylinder/head/sector geometry
          • divide cylinders by 2 and double number of heads logically
      • >8.4gig (bios)
        • kernel >= 2.0.34
        • Large disk mini howto
      • Disk Layout
        • max of 4 primary partitions
          • /dev/hda1 - first primary
          • /dev/hda2 - 2nd primary
          • /dev/hda3 - 3rd primary
          • /dev/hda4 - 4th primary
        • 1 primary can be an extended partition -- container partition
          • since the extended is a primary it is named as described above
          • logical paritions
            • /dev/hda5
            • /dev/hda6 etc
        • create partitions
          • /sbin/fdisk
            • fdisk output
          • x program
          • disk druid (Installation)
            • Menu disk partitioning during RedHat install
• scsi
  • adaptec
    • Vendor has started to support "Open source" community. Will be a while before the drivers catch up with the hardware.
  • NCR/Symbios based boards
    • Symbios
    • tekram
    • Bus Logic
    • Intel Night Shade Dual Pentium II motherboard
  • device names
    • /dev/sda first scsi disk found
    • /dev/sdb 2nd scsi disk found
    • beware of removing scsi disks as drive names may change
    • /dev/st0 -- first scsi tape drive
• Raid
  • software - MD device driver
  • Hardware
    • DPT
• Floppy
  • /dev/fd0
    • /dev/fd01440 default size
    • /dev/fd01722 ?
• IRQ
  • 1-15
    • most are reserved for system use
    • some are assigned by convention
      • 0 -- System timer
      • 1 -- Keyboard Controller
      • 2 -- cascade
      • 3 -- com 2
      • 4 -- com 1
      • 5 -- sound/lpt2
      • 6 -- floppy disk
      • 7 -- parallel port/lpt1
      • 8 -- real-time clock
      • 9 -- same as 2
      • 10
      • 11 -- pci bus
      • 12 -- ps/2 mouse
      • 13 -- math co-processor
      • 14 -- ide disk 0
      • 15 -- ide disk 1
• ports
  • serial - normally 2 connectors
    • com1
      • base io 3F8h
      • /dev/cua0
      • /dev/ttyS0
    • com2
      • base io 2F8h
      • /dev/cua1
      • /dev/ttyS1
    • com3
      • same irq as com1
      • base io 3E8h
      • /dev/cua2
      • /dev/ttyS2
    • com4
      • same irq as com2
      • base io 2E8h
      • /dev/cua3
      • /dev/ttyS3
  • parallel
    • ecp,epp/bidirectional
      • ecp -- enhanced capabilites port
        • uses a dma
        • designed for faster printers
      • epp -- enhanced parallel port
        • designed for notebooks
    • base io 38Ch or 378h
    • /dev/lp
  • ps/2
    • /dev/psaux
  • usb
  • ir
  • pcmcia
• mice
  • 2 button
    • In X must press both buttons to simulate "center" button
    • 2 button with scroll wheel
      • works with X -- use IMps/2 as mouse type
    • microsoft
  • 3 button
    • In X center button just works
    • logitech
    • mousesystems white mouse
    • belkin 3 button
    • cheap -- may not work with X as a 3 button
  • ps/2
    • /dev/mouse symbolic link to /dev/psaux
  • serial
    • /dev/mouse symbolic link to /dev/cua0
• DMA
  • 0 -- available
  • 1 -- Sound/available
  • 2 -- floppy disk
  • 3 -- ecp/parallel/available
  • 4 -- 1st DMA controller cascade
  • 5 -- Sound/Available
  • 6 -- SCSI/Available
  • 7 -- Available
• Plug and Play
  • Intended to have system automatically configure IRq,dma,base io address's. Need Plug and Play aware BIOS. Do NOT need Plug and Play aware OS. If you do NOT have a plug and play aware OS then BIOS can do most of the work. Need to tell BIOS to do the work by turning OFF Plug and Play aware OS question in BIOS.
  • /sbin/isapnp
    • /etc/isapnp.conf
• RedHat Supported Hardware List
  • note it does not say how well something is supported
  • sometimes things move off the list because they do not work as well