Re: [PARPORT] Printing unreliable using ECP/EPP

From: Adam Baker (
Date: Fri Dec 12 2003 - 17:11:44 EST

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    On Friday 12 December 2003 8:25 pm, Neil Munro wrote:

    > Interesting... BIOS=>modes
    > The odd thing is that another system (Jetway 603TCF mainboard) DOES print
    > correctly in EPP mode, so I don't think it is a cable issue, but it
    > displays the modes exactly as above, i.e. EPP is detected (and appears to
    > work) but ECP mode is not detected and ECP+EPP mode gets confused and just
    > becomes SPP.
    > I will try the ASUS mainboard again in pure EPP mode to see if it does work
    > (I'm sure I tried all 4 BIOS options, but I was tearing my hair out at the
    > time...).
    In that case you may well have hit the same problem as I did with an Asus
    board. Below is a copy of the message I posted back in June - if you can
    recompile your parport module with this test removed I'd be interested to
    know the result, just comment out the whole of the if statement after /*
    Check for Intel bug. */ in parport_pc.c

    Rather a long time ago, Sat, 30 Oct 1999, in fact Tim Waugh wrote

    >Does anybody remember why we check for the Intel ECPEPP bug? The symptom
    >is that the EPP timeout bit is _not_ set to 1 when not in EPP mode.

    >The original check is due to David Campbell, and it is found in his
    >id_probe program as well as older versions of ppa.c.

    >I can't think of what bad effects it could have. It would be nice if we
    >could get rid of the check if there really isn't anything bad that can

    but the archives contain no answer to this question. Is there anyone around
    now who knows the answer?

    The reason I ask is that on my Asus A7V333 motherboard with a ITE IT8703F-A
    Super I/O chip it fails this test even when EPP mode is enabled in the BIOS.
    I've tried deleting this test and my parport then includes EPP in it's list
    of supported modes. I presume it does really work as my parallel port scanner
    works reliably after making the change and doesn't without. The onscsi driver
    that the scanner uses appears to prefer to work with EPP if available.

    I haven't yet experimented to see if EPP is detected or if it works if it is
    disabled in the BIOS but I guess that is the next stage.

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