cent(7) Miscellaneous Information Manual cent(7)
NAME
cent - Centronics-compatible interface
DESCRIPTION
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 interface driver does no character processing; that is, it does not interpret the data being transferred between computer and periph-
eral. Therefore, all bytes sent to or received from a device are handled without alteration. The 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 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:
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:
mode 2 Automatic handshaking using only BUSY.
Minor number format:
mode 3 Bidirectional read/write used for ScanJet.
Minor number format:
mode 4 Stream mode. Data is essentially transmitted to the peripheral without any handshaking protocol.
Minor number format:
mode 5 Pulsed mode using both ACK and BUSY for automatic handshaking. Similar to mode 1 except that the data strobe line, is
pulsed for a fixed amount of time by the sender, then released.
Minor number format:
mode 6 Pulsed mode, using only BUSY for automatic handshaking. Similar to mode 1 except that the data strobe line, is pulsed
for a fixed amount of time by the sender, then released.
Minor number format:
Modes 1 and 2 support most HP *Jet series printers (LaserJet, DeskJet, QuietJet, etc.).
AUTHOR
was developed by HP.
SEE ALSO
lp(1), ioctl(2), intro(7), lp(7).
Workstations Only cent(7)