From: Baltissen, GJPAA (Ruud) (
Date: 2004-07-12 11:31:14

Hallo Andre,

> If you look at the protocol, you see that active ATN negating 
> NRFD and NDAC automatically blocks the bus .....

I changed the software so it negates NRFD and NDAC immediatly after
detecting ATN but unfortunately it didn't help. I have thought about
disabling the IRQ using ML but until now some trials weren't succesfull at
all. IMHO you only move the problem from one spot to another. Of course
there are many places were an Interrupt does no harm at all but accessing
the harddisk is INT driven as well and particulary this prevents me from
disabling the INT all the times. And IMHO the only IRQ's that could be
responsible are the Refresh- and Timer-interrupt. The first one uses
hardware to stop the CPU (IIRC) and the second one is needed for keeping a
correct time. Messing araound with the interrupt means messing around with
the time as well. But I will give it another try again....

The only other thing I can do is to build some hardware that does the trick,
something I am not happy with. The main reason I'm not happy is that I need
3 connectors: LPT, RS-232 and (Joystick or keyboard). The last one is for
supplying the needed 5V. Hmmmm, if a RS-232 can light up a LED, it should be
powerfull enough to power two 74xx IC's. Nice idea IMHO :)

   / __|__
  / /  |_/     Groetjes, Ruud
  \ \__|_\



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