my problems are I formatted an old 80386DX computer without have a boot-up disk in the first place. I realised the mistake when i boot the computer... i lost the c: drive. It allows only a: (5-1/4 drive) and b: (3-1'2 drive).
I read previous posts... that I should use FDISK to get back the hard drive c:
I tried but it read 'Incorrect DOS version'.
So I checked ver... it shows DOS 3.30 version. I don't have DOS 3.30. Why can't I use DOS 5; I thought all DOS versions will work. Please advise. Thank you.

The majority of DOS commands are 'version' dependant (they have to match command.com etc.)You might be able to get around this by using the setver command, but you'd be better off to obtain a set of DOS disks for the version that you wish to install. Fdisk alone will NOT restore the drive, you need to install (or reinstall) an Operating System, such as DOS - for that you need a boot disk! Check around this forum, there have been plenty of links posted in the past. Just what were you planning on doing with this machine without an operating system??

Thanks for explaning.
I'm trying to install DOS into the computer. But I can't get to c prompt, which I lost it when I formatted without using /s. I want to get back the c prompt and then install DOS and Windows. Is there another way to install DOS without the
c prompt (I know there is a hard drive in the computer and also it has a CD-Rom). I've a copy of DOS 5, but no DOS 3.3. Please help. Thanks again.

Ok, well your disk is already formatted, what you need is a DOS boot disk, preferably for the version of DOS you plan to install. The disk will have the hidden, system files MSDOS.SYS and IO.SYS on them (but you can't just copy those files), as well as command.com. You will also need to have SYS.COM as well. Needless to say, all these files must be of the same DOS version. Put the boot disk in the a: drive and start the computer - you should be looking at the A:>
Type 'sys c:' (no quotes) - this will tansfer the system files to the hard drive - you'll see a message 'system transferred'. Remove the disk and reboot the computer. It should show the C:>
If all went well, you've just installed a (bare bones) version of DOS. Now you just need the rest of the DOS 'external' commands. It sounds as if you are already booting from a floppy to be able to get the version number (3.3). If you want a higher version of DOS, you'll need a boot disk for that particular version (the external files wouldn't hurt either)
Hope this sheds a little light on your situation.

get you a dos 5.0 bootdisk and boot the pc with that

To jboy, Thanks a million for helping me!
THANK YOU.

To NT, Thank you too.

CYC @^o^@

If you cannot access C:, how did you find out it is version 3.3? There have to be two versions involved to get incorrect dos version, the one whose command.com is in memory and the one whose command you have tried to use. It seems to me you must be accessing C:. Incidentally, I would go into the bios and changd drive a: to 3 1/2" making B: drive 5 1/4" because you can't download a 5 1/4 boot disk.
You need to get a boot disk and start from scratch.

Just to clarify:
You cannot change the boot drive merely by going into the BIOS (at least not on the machine in question).
To do that, you'll need to install the correct drive cable, A: being after the 'twist' - also, those 5.25 drives (usu) took a different style of connector.
Then you'd enter the correct BIOS info.