[PARPORT] Daily ppdev question... difference between nibble and compat and byte mode

From: Peter Asemann (sipeasem@immd3.informatik.uni-erlangen.de)
Date: Mon Jun 02 2003 - 12:14:31 EDT

  • Next message: Tim Waugh: "Re: [PARPORT] Daily ppdev question... difference between nibble and compat and byte mode"

    Well...

    Where's the difference between the nibble and the compat mode?
    I suppose that in nibble mode you can use the "read" function which will not
    work in compat mode?
    This should make not difference if, for example, some "user land" driver
    decides to read the status lines to implement nibble mode on it's
    own, I suppose?
    Regarding byte mode, I guess PPDATADIR will only work in byte mode,
    IEEE1284_MODE_BYTE?
    So in byte mode a program that does not use read and write but reads and
    writes data and status and control register on it's own would be able to
    perform all operations possible with a tristate spp port?

    I find there's a ioctl missing which tells you if the port is in forward or
    reverse direction... but I guess if my program is interrupted by another
    program or yields the port so another program may use it, my program's
    settings regarding the direction of the port are restored... aren't they?

    Peter Asemann

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