Re: [hatari-devel] IDE IO register range access commit

[Thomas Huth <th.huth@xxxxxxxxx>]

Am Sat, 26 Sep 2020 18:57:00 +0200
schrieb Uwe Seimet <Uwe.Seimet@xxxxxxxxx>:

> Hi,
> 
> > I've now had a look, and I think I've successfully fixed the issue
> > reported by Uwe, and another crash that occurred when there was
> > only a secondary IDE drive attached, without a primary one.
> > 
> > BTW, the hard disk driver Cecile now also seems to work fine in
> > Falcon mode when no IDE drive has been specified (it used to crash
> > with a bus error before) :-)  
> 
> The crash is gone, but strictly speaking there is still something
> wrong, or at least unusual:
> 
> When I assign an IDE slave drive only, without master drive, the IDE
> interface is available and the slave drive is accessible. But a slave
> without master is not supported by IDE.

Honestly, that's also what I thought first. But apparently some hard
disk drivers can deal just nicely with that situation...

Also on https://en.wikipedia.org/wiki/Parallel_ATA they write:

"Master and slave clarification

[...] Since ATA-2 the two devices are referred to as "Device 0" and "Device 1", respectively. This is more appropriate since the two devices have always operated, since the earliest ATA specification, as equal peers on the cable, with neither having control or priority over the other.

It is a common myth that the controller on the device 0 drive assumes control over the device 1 drive, or that the device 0 drive may claim priority of communication over the other device on the same ATA interface. In fact, the drivers in the host operating system perform the necessary arbitration and serialization, and each drive's onboard controller operates independently of the other."

.... and that rather sounds like the secondary drive could also operate
without the primary one?

 Thomas