gdc(7)
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gdc Special File
Eclipse MV/family graphics display controller
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DESCRIPTION
This device driver supports one or more Data General GDC/1000
graphics display controllers. The device is accessed using the
standard open, close, read, write, ioctl, and select system
calls. Data and commands may be transferred to and from this
device using the standard "read" and "write" system calls. The
status of the device may be obtained and set using "ioctl".
The open system call performs a warm start of the GDC/1000
device. If for any reason the "ready" bit in the device state is
not on after the warm start, the error ENXIO is returned and the
device is not opened. The open system call will also fail if
data channel map slots can not be allocated, or if the device is
already open. These errors return ENXIO.
The close system call makes the GDC/1000 available to be opened
again.
The read system call returns data from the GDC/1000. The
GDC/1000 must have previously had issued to it via the write
system call a command that prompts it to return data. If the GDC
times out during the read operation, or the status register of
the GDC shows an error, the read system call will return the
error status EIO.
The write system call transfers a byte sequence from the caller's
buffer to the GDC/1000. The byte sequence is interpreted only by
the GDC/1000 and not by the DG/UX system. The length of the byte
sequence is the size of the caller's buffer. If the GDC times
out during the write operation, or the status register of the GDC
shows an error, the write system call will return the error
status EIO.
The ioctl system call may be used to get or set the status of the
GDC/1000 device. The GDCSET ioctl command sets the status from
the "argument", while the GDCGET command returns the status in
the "argument". See the description of the status fields in
<sys/gdc.h>.
Select always returns READY for both read and write operations.
FILES
DG/UX 4.00 Page 1
Licensed material--property of copyright holder(s)
gdc(7)
/dev/gdc* gdc device nodes
/usr/include/sys/gdc.h include file with structure and constant
definitions
SEE ALSO
GDC/1000 Graphics Display Controller User's Manual (014-701004)
DG/UX 4.00 Page 2
Licensed material--property of copyright holder(s)