Re: [PARPORT] ECP printing problem

From: Stephen Mollett (
Date: Thu Aug 22 2002 - 15:31:19 EDT

  • Next message: Blaise Gassend: "Re: [PARPORT] ECP printing problem"

    On Wednesday 21 Aug 2002 18:14, Z F wrote:
    > Do you think that the problem with ECP printing is related to the
    > software or it is the printer which does not understand ECP protocol?

    I'm not sure. It could be either. Or, if the printer is 'daisy-chained' off
    the SuperDisk drive, it could be to do with the extra connectors and
    cable-length affecting signal-integrity in high-speed ECP mode.

    I seem to remember that I always found printing through my PP drive somewhat
    unreliable, both under Windows and Linux. I eventually bought a
    USB-to-Parallel cable for the printer which solved the problem nicely.

    >> ... the SuperDisk almost certainly uses EPP mode, and will
    >> work substantially slower if ECP mode (or ECP+EPP mode) is selected.
    > I must say that while SuperDisk works, it consumes huge amounts of CPU
    > resources and it is practically impossible to do anything while the
    > disk is in use. System load goes to 2.00 on my Pen4 1.7GHz even with
    > nice=20 parameter.

    I think that's much the same for any parallel-port disk device. My SyQuest
    drive does the same if I do large uninterrupted reads/writes. Recent kernels
    seem to be much better in that respect, though. I'm using 2.4.19 now and,
    although the system becomes a little bit choppy at times, I can still use KDE
    successfully while the drive is being accessed. Kernel preemption may also

    For reference, my Panasonic IDE LS-120 SuperDisk drive (double-speed, 1440rpm)
    gives me about 825kB/s for the first 8MB of an LS-120 disk. You should be
    able to cram about 1MB/s through the port in EPP mode (according to
    benchmarks I ran on the SyQuest drive under Windows some years ago) but the
    Linux driver seems to struggle to reach 350kB/s. Or maybe it's just the drive
    getting old :-)

    >> You should be able to see something in your dmesg output from the
    >> SuperDisk's
    >> protocol driver that tells you what mode it's currently using...
    >> Example from my EPAT-based SyQuest drive
    >> [snip]
    > I guess you are talking about "mode 5(EPP-32)" in your example which
    > would change when switching between EPP and ECP port modes?

    Yes, sorry, I forgot to point out that bit. It would drop back to "mode 0
    (4-bit)" or something if the port was in ECP or ECP+EPP mode. (It's a while
    since I last tried it.) And the drive would come screeching to a halt, or
    very nearly - IIRC, I used to get about 50kB/s when I attached the drive to
    my old non-EPP-capable 486 PC.


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