cent(7)                                                             cent(7)
                              Workstations Only



 NAME    [Toc]    [Back]
      cent - Centronics-compatible interface

 DESCRIPTION    [Toc]    [Back]
      cent is a simple, widely used communication protocol most commonly
      associated with printers, plotters and scanners.  It is an eight-bit
      parallel data interface with additional control signals from the host
      computer, and status signals from the peripheral.

      The cent interface driver does no character processing; that is, it
      does not interpret the data being transferred between computer and
      peripheral.  Therefore, all bytes sent to or received from a device
      are handled without alteration.  The cent interface driver always
      operates in raw mode; therefore, any desired data interpretation must
      be performed by a user program (such as the ``lp'' spooler in
      conjunction with an appropriate model file).  The cent driver supports
      six different handshake modes for data transfer.  The last four bits
      of the minor number of the device special file specify the mode used.
      The format of the device minor number is:

           0xII000A

      where each letter after the ``0x'' prefix represents a single
      hexadecimal digit, as follows:

      II   Specifies the instance number of the centronic interface.

      000  Always zero.

      A    Specifies the handshake mode.  The handshake modes are:

                mode 1    Automatic handshaking using both ACK and BUSY.
                          Minor number format: 0xII0001.

                mode 2    Automatic handshaking using only BUSY.
                          Minor number format: 0xII0002.

                mode 3    Bidirectional read/write used for ScanJet.
                          Minor number format: 0xII0003.

                mode 4    Stream mode.  Data is essentially transmitted to
                          the peripheral without any handshaking protocol.
                          Minor number format: 0xII0004.

                mode 5    Pulsed mode using both ACK and BUSY for automatic
                          handshaking.  Similar to mode 1 except that the
                          data strobe line, nSTROBE, is pulsed for a fixed
                          amount of time by the sender, then released.
                          Minor number format: 0xII0005.





 Hewlett-Packard Company            - 1 -   HP-UX 11i Version 2: August 2003






 cent(7)                                                             cent(7)
                              Workstations Only



                mode 6    Pulsed mode, using only BUSY for automatic
                          handshaking.  Similar to mode 1 except that the
                          data strobe line, nSTROBE, is pulsed for a fixed
                          amount of time by the sender, then released.
                          Minor number format: 0xII0006.

           Modes 1 and 2 support most HP *Jet series printers (LaserJet,
           DeskJet, QuietJet, etc.).

 AUTHOR    [Toc]    [Back]
      cent was developed by HP.

 SEE ALSO    [Toc]    [Back]
      lp(1), ioctl(2), intro(7), lp(7).


 Hewlett-Packard Company            - 2 -   HP-UX 11i Version 2: August 2003