Can DOS boot to a hard drive other than HDA1?

Question

I would like to experiment with DOS and would like to create a bootable partition on my hard drive (SDA) SATA device.

I created a 1G FAT32 formatted partition on my SATA hard drive (SDA) and tried to make a FreeDOS partition on it. I downloaded the FreeDOS CD-ROM. When I boot to the CD-ROM it does not see either of my two SDA or SDB devices :(

I also made a bootable MS DOS 6.21 USB and tried to copy it to the hard drive using the sys command. It can see the SATA (SDA) drive but when I attempt to copy the system to it, I get an error "wrong OS version".

All the information I have found says DOS can only boot to HDA1 (IDE). Must it be a IDE device or can it be a (SD) SATA device?

I have copies of MS-DOS, FreeDOS, RxDOS, and MxDOS. Would any of these be able to boot to a SATA device? Would any of these be able to boot to something other than the first partition?

Another way to ask this question is "How can I make a bootable DOS partition on a SATA (SD) hard drive device" (it's a laptop with no floppy).

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Update

After formatting to FAT16 as suggested below (thx Spektre), FreeDOS recognized my DOS partition and loaded. I am currently trying to configure GRUB 2 to boot to it and will update once I get it figured out. GRUB 2 instructions also says it can boot to another drive if it remaps the drive designation using the "map" command.

Answer 1

All the information I have found says DOS can only boot to HDA1 (IDE). Must it be a IDE device or can it be a (SD) SATA device?

There are two things to consider: whether the computer can boot from a device (which depends on its firmware), and whether DOS can access the device (which depends on “legacy” BIOS support in the shape of interrupt 0x13 services, ignoring the enhanced disk drive services which Windows can use, and the disk layout). On older PCs, DOS worked fine with MFM, RLL, IDE, EIDE, SCSI, SATA etc. drives, as long as the controller included an option ROM to provide the necessary support when the motherboard BIOS didn’t include it.

So the trick is to configure the system’s firmware so that it provides the services DOS needs, and then set the disk up so that the computer can boot from it and DOS can access it.

On modern systems using SATA, a boot environment compatible with DOS requires two specific items in the firmware: “legacy-mode” SATA support, and a Compatibility Support Module. Both of these are starting to disappear; some new PCs can no longer boot DOS on their own (notably, systems certified connected standby don’t include a CSM). On systems with a CSM, you need to go into your firmware setup, select legacy mode SATA support, and enable the CSM if necessary (the option to do this depends on your specific firmware; there might not even be an option, some systems load the CSM automatically if they find an MBR-partitioned disk). Note that changing the SATA mode may have adverse effect on Windows installations, and enabling the CSM will disable Secure Boot.

Then comes the disk format. You’ll need to use MBR-style formatting, not GUID partition tables. If you have an empty disk, the best way to proceed is to boot DOS and let it set the disk up; this will ensure that it uses the disk layout it expects, and writes all the information it needs to the partition table. If you need to repartition, use fdisk under Linux, with the -c=dos option; read the manpage carefully, and instead of creating a DOS partition, move partitions around to leave free space at the start of the disk, then use DOS fdisk to create a DOS partition in the free space.

Answer 2

"How can I make a bootable DOS partition on a SATA (SD) hard drive device" (it's a laptop with no floppy).

First of, SDx is just a naming convention under Linux, made to purposefully hide hardware details. It can be as well a USB drive, as it can be some IDE or many other ways of connection. The naming is not related to SATA, but meant originally SCSI-Drive (in contrast to IDE which where called originally HDx).

From an OS perspective, at least as long it's using BIOS routines, SATA looks exactly like any other drive. It only differs when the OSes own drivers take over.

For booting the real connection used is important, and to be defined in your computer's BIOS setup. Here a drive can be selected (or a sequence thereof). It's fine to put up an SATA drive here for booting.

Like in the good old days of floppies, the BIOS will try to read the first sector and start any program found. One speciality is if there's a partition block, then it'll look thru the list of (up to four) primary partitions and try to load from the first one marked bootable.

It gets even more complex, as there is a newer version, called GUID partition table. The later might be something the boot loader of the various DOSes you try does not understand - GUID is only in use since the mid/late 2000s. If your drive goes past 2 TiB, it most certainly has a GUID partitioning scheme.

GUID partitioning do feature a pseudo MBR table for compatibility, which marks the whole drive as used and unavailable. In combination with older OS this might result in not 'seeing' the drive.

To raise chances for older OS to boot, partition the HD either as one drive (like a floppy) or using an MBR. here also just put in a single partition, possibly with less than 32 MiB size, as depending on the age or the DOS used, it may not go well with some of the newer extensions.

Having done so should make it possible to install an old DOS.

Then again, under Linux, it might as well be less work to install a virtual machine, using a disk image from that DOS.