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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: spirantho on May 01, 2013, 10:28:55 AM

Title: IO_CH_RDY on an A4000 - does it go anywhere?
Post by: spirantho on May 01, 2013, 10:28:55 AM

Hi people,
Still trying to work out why this 4000 just doesn't grok ATAPI devices at all.

I've noticed that pin 27 (IO_CH_RDY) on the IDE bus seems to go nowhere on the schematics - is this an error? Is it supposed to connect somewhere? Seems a bit daft to have a signaled pin on the schematic that goes nowhere at all... and may be (possibly) related to my problem.

Anyone know?
Thanks!

Title: Re: IO_CH_RDY on an A4000 - does it go anywhere?
Post by: freqmax on May 01, 2013, 03:07:11 PM

IO_CH_RDY is meant to make the bus controller (host) wait for slow units.

Title: Re: IO_CH_RDY on an A4000 - does it go anywhere?
Post by: spirantho on May 01, 2013, 04:15:46 PM

Yes, that's what I thought. The same pin on the A1200 is called "/WAIT".

But it doesn't seem to connect to anything?!

Title: Re: IO_CH_RDY on an A4000 - does it go anywhere?
Post by: freqmax on May 01, 2013, 04:25:16 PM

The designer betted that all units to be used would be fast enough?

Title: Re: IO_CH_RDY on an A4000 - does it go anywhere?
Post by: SpeedGeek on May 01, 2013, 07:48:14 PM

If you check the ATA specs. you should find that I0_CH_RDY is optional for PIO 0-2 but necessary for more advanced PIO modes.

Title: Re: IO_CH_RDY on an A4000 - does it go anywhere?
Post by: freqmax on May 01, 2013, 08:29:12 PM

And A4000 only uses PIO 0-2 ? ;)