EDUSAT SESSION FOR ADVANCED MICROPROCESSOR EC54

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EDUSAT SESSION FOR ADVANCED MICROPROCESSOR
(EC54) Date 13.12.2005 Session IX Topic LPT and
USB Faculty Anita Kanavalli MSRIT
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Parallel Printer Interface

• The parallel printer interface is located on the
  rear of the PC
• LPT stands for Line printer
• The printer interface gives access to eight
  lines that can be programmed to receive or send
  data

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Parallel Printer Interface

• Port details
• The parallel port LPT1 is normally at I/O port
  addresses 378H, 379H and 37AH
• The secondary port(if present) is located at
  278H, 279H and 27AH

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Parallel Printer Interface

• The Centronics interface implemented by the
  parallel port uses two connecters
• One is 25 pin D type on the back of the PC
• The other one is 36 pin on the back of the
  Printer

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Parallel Printer Interface

• Connectors DB 25

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Parallel Printer Interface

• Connectors Centronics 36 pin

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Parallel Printer Interface

• The parallel port can work as both transmitter
  and as well as receiver
• Other than printers CD ROMs can also be
  interfaced through parallel port.

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Parallel Printer Interface

• The contents of the Data Port 378H
• Connects to bits DO-D7 (pins 2-9)

7 6 5 4 3
2 1 Bits
9 8 7 6 5
4 3 Pins
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Parallel Printer Interface

• The contents of the Status Register 379H
• This is read only port that returns information
  from the printer

7 6 5 4 3
2 1 Bits
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Parallel Printer Interface

Bit 3 NERROR 1 no error Bit 4 ONLINE
1Online Bit 5 PAPER 1out of order Bit 6 ACK
1acknowledgement Bit 7 NBUSY 1printer not busy
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Parallel Printer Interface

• The contents of the Status Port 37AH

7 6 5 4 3
2 1 Bits
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Parallel Printer Interface

Bit 0 STR pulse high to print Bit 1 ALF 1line
feed by printer Bit 2 INI 0initialize
printer Bit 3 DSL 1select printer Bit 4 IRQ
1enabled Bit 5 Bidirectional (0output, 1input)
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Universal Serial Bus

Universal Serial Bus (USB) allows the addition of
a new device to a PC by plugging it into the back
of the machine or daisy-chaining it from another
device on the bus. The device is immediately
available for use (no rebooting required) and
often does not need a device driver to be
installed.
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Universal Serial Bus

• A big advantage of USB devices, apart from their
  much greater speed, is that USB devices configure
  themselves automatically.
• Another benefit is that because USB devices do
  not require IRQ settings, DMA channels, or I/O
  settings, COM and LPT ports currently occupying
  an IRQ can be freed up, making more IRQ
  interrupts available for other uses.

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Universal Serial Bus

• Another advantage of USB is that it is a standard
  port and can support just about any type of
  device, including keyboards, mouse, serial
  peripherals (e.g. modems), printers, audio
  input/output, joysticks, digital cameras,
  scanners, external hard disks and CD burners.

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Universal Serial Bus

• USB uses a four-wire cable interface.
• Two of the wires are used in a differential mode
  for both transmitting and receiving data, and the
  remaining two wires are power and ground.
• The source of the power to a USB device can come
  from the host, a hub, or the device can be "self
  powered."

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Universal Serial Bus

• There are two different connector types on each
  end of a USB cable. One of these connectors is
  for upstream communications, and the other for
  downstream. Each cable length is limited to about
  5 meters.

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Universal Serial Bus

• The connector
• Two types of female connectors are used
• USB Data
• The data signals are biphased
• Uses NRZI data encoding for transmitting packets
• Bit stuffing is used for synchronization

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Universal Serial Bus

• NRZI Non-Return-to-Zero-Inverted Encoding A
  '0' is encoded as no change in the level. However
  a '1' is encoded depending on the current state
  of the line. If the current state is '0' low
  the '1' will be encoded as a high, if the current
  state is '1' high the '1' will be encoded as a
  low. Used with FDDI and USB for example.

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Universal Serial Bus


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Universal Serial Bus

• USB commands
• The type of packets and contents found in the USB
• Token Packet

8 Bits
7 Bits
4 Bits
5 Bits
PID
ADDR
ENDP
CRC5
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Universal Serial Bus

• USB commands
• Start of Frame Packet

8 Bits
11 Bits
5 Bits
PID
Frame Number
CRC5
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Universal Serial Bus

• USB commands
• Data Packet

8 Bits
1 to 1023 Bits
16 Bits
PID
Frame Number
CRC16
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Universal Serial Bus

• USB commands
• Handshake Packet

8 Bits
PID
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Questions

1 What data rates are available for use with the
USB 2 What is the maximum cable length for use
with the USB 3 How many device addresses are
available on the bus 4 What is NRZI encoding? 5
How long can a data packet be on the USB?
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Introduction to 80386

• 80386 microprocessor is 32 bit processor
• Its Features are
• multitasking
• memory management
• virtual memory
• software protection
• large memory system