IBM PC/AT Problem

[vibriel123]

I have an old IBM PC/AT (compatible), with 720K and 1.2MB Teac drives which connected to an controller card (strange connector : like --- ---------), EGA card and monitor, AT-style keyboard (no Windows and Rightclick button), an AT-style keyboard connector, 1 Harddisk (ST238R Seagate 32MB).

1. The harddisk is detected by BIOS, but not by the DOS. I have tested 3 programs : fdisk, and 2 any other programs and they said that they can't detect any phisycal drives.
2. I can't use DOS 7, why?
3. Can I change that 720K into an 1.44MB ones? I have the 1.44MB floppy (Panasonic 2005) but the connector is IDE!
4. If I typed B: on DOS, it says "Insert disk on drive B" and after I pressed Enter, the drive B is my A: drive. Same. So I can't access my 5.25" drive. What can I do?

 

[hargle]

1. The harddisk is detected by BIOS, but not by the DOS. I have tested 3 programs : fdisk, and 2 any other programs and they said that they can't detect any phisycal drives.

You could try spinrite to see if it can detect any hard drive out there and bring it back to life. I'd dump the hard drive and switch to IDE. You should be able to get an IDE hard drive controller if your motherboard doesn't already have one. Then I'd just go get another one-you can easily find free/very cheap drives on craigslist or geeky friends. I have 10gig drives in my 286,386 and 486 using disk manager software to expand out the drive size for old computers. Works great!

2. I can't use DOS 7, why?

it is probably using 386 instructions, which your computer doesn't support.
I use 6.22 on most of my old machines, but I think the later DR-DOS works well too.

3. Can I change that 720K into an 1.44MB ones? I have the 1.44MB floppy (Panasonic 2005) but the connector is IDE!

That's probably an LS-120 drive, which I doubt you will be able to use. (you need BIOS support for those, even though you may have an IDE controller, it still won't work.) You need a true 1.44mb floppy drive with a 34pin connector on it. Those really should be easy to find for free/cheap too.
It will still depend on the controller card as to if it can support 1.44mb floppies though.

4. If I typed B: on DOS, it says "Insert disk on drive B" and after I pressed Enter, the drive B is my A: drive. Same. So I can't access my 5.25" drive. What can I do?

check setup, cables and power. setup might only have 1 drive enabled or the controller card you're using doesn't support high density or is jumpered incorrectly. That could be a multitude of things.