NAME

cent − Centronics-compatible interface

REMARKS

This manual entry applies only to peripherals connected to the cent interfaces found on Series 300, 400, and 700 systems. 

DESCRIPTION

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 model for the cent interface drivers is simple in that no character processing is done; i.e., no interpretation is applied to the data being transferred between computer and peripheral.  Therefore, all bytes sent to or received from a device are handled without alteration.  In other words, the cent interface drivers always operate in raw mode which means that any desired data interpretation must be performed by a user program (such as the lp spooler in conjunction with an appropriate model file). 

DEPENDENCIES

Series 300/400

A wide variety of control functions are supported.  See Device I/O Library (gpio∗(3I), hpib∗(3I), and io∗(3I)), entries in Section 3 of this manual.

Series 700

The Series 700 cent driver supports six different handshake modes for data transfer.  The last four bits of the minor number of the device special file specify which mode is used.  The format of the device minor number is:

0xSEF00A

where each letter represents a single hexadecimal digit as follows:

0x Preamble to a hexadecimal number. 

S Specifies the system bus module number ( 2 for core I/O). 

E Specifies the EISA slot number: ( always 0 for core I/O). 

F Specifies the function number.  Always 6 for the Core I/O parallel interface. 

00 Always 0. 

A Specifies the handshake mode.  The handshake modes are:

mode 1 Automatic handshaking using both n ACK and BUSY.  Minor number format: 0xSEF001. 

mode 2 Automatic handshaking using only BUSY.  Minor number format: 0xSEF002. 

mode 3 Bidirectional read/write used for ScanJet.  Minor number format: 0xSEF003. 

mode 4 Stream mode.  Data is essentially transmitted to the peripheral without any handshaking protocol.  Minor number format: 0xSEF004. 

mode 5 Pulsed mode using both ACK and BUSY for automatic handshaking.  Similar to mode 1 except that the data strobe line, n STROBE is pulsed for a fixed amount of time by the sender, then released.  Minor number format: 0xSEF005. 

mode 6 Pulsed mode, using only BUSY for automatic handshaking.  Similar to mode 1 except that the data strobe line, n STROBE is pulsed for a fixed amount of time by the sender, then released.  Minor number format: 0xSEF005. 

Modes 1 and 2 support most printers belonging to the ∗Jet series (LaserJet, DeskJet, QuietJet, etc.). 

AUTHOR

cent was developed by HP. 

SEE ALSO

lp(1), ioctl(2), intro(7), lp(7). 

System Adminstrator manuals included with your system. 

Hewlett-Packard Company  —  HP-UX Release 9.0: August 1992