🚀 go-pugleaf

In <1993Jan20.181528.9501@cs.sfu.ca> welman@cs.sfu.ca (Chris Welman) writes:
| Yes, I did see this in plp.h.  On the read side I'm issuing PLPIOCRESET,
| PLPIOCREAD, and PLPIOCRTO (read timeout), in that order.  No luck - the
| write call just hangs (or times out), presumably waiting for something
| to occur.  I'm also doing a PLPIOCSTATUS to query the port status on
| both ends, and this tells me that the "printer" is considered to be offline, 
| which makes me wonder whether the Indigo is expecting the "peripheral" to
| assert a signal on pin 13 (ONLINE) before anything will work.  Obviously
| there is something I'm overlooking...

Thinking about it more, I think I know what the problem is.  In the
bidirectional mode, you probably can't just hook the two ports up
directly, because it uses the conventions used by the Ricoh parallel
port scanner, and they are somewhat different than normal printers.

I need to get some hardware specs to get more detail; let me know if
you really want to pursue it by email.

| By the way, there is a second undocumented ioctl in plp.h, PLPIOCSETMASK.
| What does this do, and is it of any use to me?  

Nothing.  It is there for compatibility with the 4D/20 and 25, because
some programs used it and didn't like getting an error on that ioctl.

Here is the comment from the 20/25 driver (the hardware didn't support
this in later versions, and it was never much used):

	/* Set printer abort mask: if any status bits match
	 * set bits in the mask, then printing stops.  This
	 * can be used to cause printing to abort on paper out.  */
	case PLPIOCSETMASK:

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Let no one tell me that silence gives consent,  |   Dave Olson
because whoever is silent dissents.             |   Silicon Graphics, Inc.
    Maria Isabel Barreno                        |   olson@sgi.com