|There is a misunderstanding...|
I have built a floppy that boots in either ahci or ide sata controller mode.
I use both drivers..gcdrom.sys (ide) ahci.sys (ahci) depending upon the state of the controller ONLY ONE of them errors out. ie... "no drive found" This way in either mode I get Cd drive letter assigned with access.
I then burn a bootable Cd (1.44 emulation) using the floppy as boot image. I am then able to put up to 700Mb in the iso data section of the Cd.
I then boot from this Bootable Cd with the sata controller in IDE mode and it works fine. Full boot with with Cd access.
I then only change the sata controller to AHCI mode and try to boot from the same Cd when the bios is finished I get "non system disk, press any key"
The problem is that when the bios hands off the boot process to the Cd Ms Dos 6.22 can't handle (probably IO.sys) ahci Cd access and therefore does not even load.
I have also obtained an image from allbootdisks.com (DOS6.22_bootdisk.iso) that has the same result.. works with sata controller in ide mode but not in ahci.
One thing to keep in mind is that ahci.sys is a Cd driver used with mscdex.exe not a controller driver. I have a sata hard disk that is bootable (Ms Dos 6.22 2GB-FAT16 partition) with access no matter what mode the controller is in or what method I boot from ie..Hd, Floppy, Cd except Cd ahci controller mode.
[AHCI] mode booting
[Hard Disk] ahci.sys provides Cd access.
[Floppy] ahci.sys provides Cd access.
[Cd] no boot
[IDE] mode booting
[Hard Disk] gcdrom.sys provides Cd access.
[Floppy] gcdrom.sys provides Cd access.
[Cd] gcdrom.sys provides Cd access.
oakcdrom.sys works with my Samsung Cd/DVD-RW drive, gcdrom.sys is a more universal driver.