Re: [PARPORT] writing data to the parallel port

From: Tim Waugh (
Date: Wed May 10 2000 - 12:41:22 EDT

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    On Fri, May 05, 2000 at 01:16:34PM -0400, Nordic Boy wrote:

    > So, basically, it claims the port, then causes the switch to go the
    > appropriate connector. It then gets a character from the user buffer.
    > The delay is there so the printer can catch up. This is sort of the
    > problem. I cannot seem to get a reliable indication of whether the
    > printer is still busy or not. If busy is low (the loop to make sure that
    > the busy low isn't spurious), then the printer should be ready for the
    > next character, right? So then if I send it the next character, it
    > doesn't always get there unless my delay is exhorbitently large.
    > Where can I get more information on this?

    In the back of IEEE 1284 there is a discussion about why compatibility
    mode is bad, which might shed some light on it. Basically there are
    several subtly different ways of doing the handshake, only one of
    which is reliable.

    Also, take a look at the comments by Andrea at the top of lp.c.


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