Re: [Freedos-devel] IDE CDrom/Dvd

[Alain M. <al...@po...>]

Hi, I made some tests:

I have prepeared a Boot floppy (and a CD with the image) with a boot 
menu and different drivers, here is what I got from a very small sample:

UIDE.SYS worked every time

AHCI.SYS did not work on my SATA machine, aparently it works only with 
specific Intel chips. It shows an Intel message.

OAKCDROM.SYS worked only and with all IDE/CDROM, as expected.

So UIDE is the best, by far. I will keep AHCI as optional anyway because 
there *could* be a mahine with AHCI only...

Thanks for UIDE,
Alain

PS: and Thanks for FreeDOS to :)


Em 25-04-2010 11:25, Johnson Lam escreveu:
> On Sun, 25 Apr 2010 15:16:14 +0200, you wrote:
>
> Hi Bernd,
>
>> To make a long story short: Jack R Ellis has had a number of drivers
>> developed for access to optical units and discs, most of this software
>> has sourcecode available. His latest is UIDE.SYS which should support CD
>> drives also on Serial-ATA  (possibly in AHCI-mode, or just IDE-emulation).
>
> UIDE have no AHCI support, only "Native IDE" or "Legacy IDE"
> supported, I've asked him the reason, his answer below:
>
> [quote begin]
>
> UIDE does benefit from usually having a LOT of "rotational
> latency" time, between disk transfers, so the next transfer will be
> set up and begun long before the disk can "rotate" back to the first
> sector of that new transfer.
>
> AHCI tries to "help" with this by "chaining" disk commands, so when
> one disk command ends, the next in the "chain" can be begun without
> the disk driver needing an interrupt or more processing.   However,
> AHCI requires "asynchronous" I-O, like Windows uses, NOT "one at a
> time" I-O like DOS uses.   So, I doubt AHCI will ever see a lot of
> use under DOS -- I see no reason for it in UIDE, and I think other
> disk-driver writers will probably feel the same.
>
> [quote end]
>
>
> Rgds,
> Johnson.