READER(4,F)                 AIX Technical Reference                 READER(4,F)



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reader



PURPOSE

Supports the IBM virtual card reader driver.

SYNOPSIS

# include <sys/devinfo.h>
# include <sys/b370/crp.h>

DESCRIPTION

While punch cards are obsolete in a UNIX environment, some VM software provides
extensive file transfer and communication facilities using the concept of
"virtual cards".  To interface to this mechanism, AIX/370 provides a driver for
a virtual card reader device.

The special files used to read from the card reader are of the form /dev/rdr#,
where # is the device unit number.  They are unique to AIX/370.

The card reader can only be opened for reading.  When read, the virtual deck in
the reader is read, one record per read, up to the maximum size of the buffer
specified.  If the device is closed before all of the cards have been read, the
remaining cards are flushed.

No IOCTL operations are available besides the standard IOCTYPE and IOCINFO
commands.

ERROR CONDITIONS

In addition to the errors listed in "ioctlx, ioctl, gtty, stty,"  "open, openx,
creat," and "read, readv, readx," system calls to this device can fail in the
following circumstances:

ENXIO     Attempt to write to the reader.

ENXIO     The reader is not currently closed.

EIO       The I/O from the reader failed during the operation.

RELATED INFORMATION

In this book:  "ioctlx, ioctl, gtty, stty," "open, openx, creat," and "read,
readv, readx."







Processed November 7, 1990        READER(4,F)                                 1