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					Serial, Parallel and other I/O
          Interfaces



            CIS 145
     Microprocessor Servicing
         Kelvin Kempfer
                     Outline

•   Standard I/O Ports
•   Parallel Ports
•   Serial Ports
•   USB
•   PS/2
                 Standard I/O Ports
• VGA (Video Graphics Array)
• Parallel Ports
    – Used for local printers
•   Serial Ports
    – Console connection
• Game Port
    – Joystick
• PS/2
    – Keyboard and mouse
• USB
    – Multiple Peripherals
           Standard I/O Ports
               D-Shell Connectors

• Female Receptors       • Male   Receptors
  – VGA                    •Serial Ports
  – Parallel
  – Game
          Standard I/O Ports
                 Female Ports
               Pin Arrangement

VGA - 3 rows each having 5 openings
MGA & CGA - 2 rows each having 5 openings
Parallel - 2 rows; 1 row of 13 and 1 row of 12
Game Port - 2 rows; 1 row of 8 and 1 row of 7
          Standard I/O Ports
                   Serial Ports
                   Male Ports
                Pin Arrangement
25-pin - 1 row of 13 and 1 row of 12

9-pin - 1 row of 5 and 1 row of 4
                Parallel Ports
•   Peripheral Devices
•   Operation
•   IBM Version
•   Faster and Better Parallel Ports
•   LPT Handles
           Peripheral Devices
•   Printers
•   X-Y Plotters
•   Computer-to-computer systems
•   Removable disk backup systems
•   Optical scanners
                Operation

• Address on the bus = Port address



• Port’s Address Setting
  – jumpers
  – DIP switches
  – Firmware/PnP
                     Operation
• Data-out
  – microprocessor places a data word on the data
    bus
  – sends an I/O write signal to the port
• Data available strobe
  – port applies to the peripheral
• Data-in
  – transfers data
               IBM Version

•   Introduced 1987 (PS/2)
•   Bi-directional parallel port
•   Commonly found in PC-compatible systems
•   8-bit parallel data and 9 I/O control lines
 Faster and Better Parallel Ports
• Enhanced Parallel Port (EPP)
  – Fast Mode Parallel Port
  – IEEE 1284 standard
  – common on IBM machines
• Enhanced Capabilities Port (ECP)
  – requires special hardware logic
  – IEEE 1284 standard
  – ECP can be turned into EPP or standard
    unidirectional parallel ports via BIOS
                IEEE 1284
• Defines the electrical signaling behavior
• Standardizing the behavior between a PC
  and an attached device
• hardware and line control-only standard
• Allows much higher throughput in a
  connection
  – printer cable uses twisted-pair technology
• A new connector (1284 Type C)
  – found on HP’s printer line
              LPT Handles
          LPT1                  LPT2
• address 3BCh or 378h • address 378h or 278h
• IRQ7                   • IRQ5
• Parallel ports located
  on video display cards
  are normally assigned
  3BCh
                Serial Ports

•   Serial Transmission Modes
•   Serial Interface ICs
•   Serial Standards
•   DOS Serial Port Names
    Serial Transmission Modes

• Parallel-in, Serial out (PISO)



• Serial-in, Parallel out (SIPO)
   Serial Transmission Modes
• Synchronously
  – in conjunction with a synchronizing clock pulse


• Asynchronously
  – without an accompanying clock pulse
          Serial Interface ICs
     Asynchronous               Synchronous
• Asynchronous          • Universal
  Communication           Synchronous/Asynchronous
  Interface Adapters      Receiver/Transmitters
  (ACIAs)                 ( USARTs)
• Universal
  Asynchronous
  Receiver/Transmitters
  (UARTs)
    DOS Serial Port Names
Either RS-232 port may be designated as
  COM1, COM2, COM3, COM4

COM1      COM2       COM3       COM4

3F8h       2F8h       3E8h      2E8h

IRQ4      IRQ3       IRQ4       IRQ3
                    USB Ports
• Allows for hot-swapping and is hot-pluggable
• Version 2 allows for up to 480Mb/s
   – Backward compatible with slower USB devices
• USB host controller
   – As many as 127 USB devices
      • Hub
   – Windows 95 OSR 2.1 first to support
      • Windows NT does not
                  IEEE 1394
•   Commonly know as FireWire and i.Link
•   Supports speeds as high as 1.2Gbps
•   Likely to replace SCSI
•   Uses Isochronous data transfer
    – Information transferred without breaks
• Windows 98, 2k and XP support IEEE 1394
            USB Compared to FireWire
                       IEEE-1394
                      (a.k.a. i.link;FireWire)   USB 1.1            USB 2.0
PC-host required              No                  Yes                 Yes
Max. # of devices             63                  127                 127
Hot-swappable                 Yes                 Yes                 Yes
Max. Cable length             4.5m                5m                  5m
Transfer rate                 200Mbps             12Mbps            480Mbps
Future trans. rates           400Mbps             None                None
                              800Mbps
                              1Gbps
Typical devices               DV camcorders       keyboards   all USB 1.1 devices
                              digital cameras     mice         digital cameras
                              HDTV                joysticks    camcorders
                              high-speed stuff     printers    high speed stuff
          Keyboards/Pointers
• PS/2
  – Sometimes called mini-DIN
     • 6 pins
• DIN connector
  – 5 pins
  – AT Keyboard Port
• USB port
  – Wireless connection

				
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