IBM/AT DOS Bootloading

[linuxsuperuser]

Hey guys!
I'm restoring an IBM/AT. Its original MFM 30mb drive has crashed. To replace it I got a IDE + floppy ISA card which works fine. I managed to boot DOS 6.11 (Should be 5!) of 3.5 disks with the new fd controller on the ISA cards.
My New HD is actually using a CF to IDE converter with a 64 MB cf card.

Heres where the trouble began.

Used GSETUP.EXE (Generic BIOS config) to set Drive C type. Apparently I can't define my Own Harddrive! I'm not sure if this is gsetup or a limitation in the AT. Defined my HD with a memory value of close but still under 64mb.

DOS installed fine, rebooted then,
"Missing Operating System" Before this I can see the Activity lights on the CF card flashing.
From research online, I know this error is usually cause by selecting the wrong drive type even though scandisk checks out, and I can use files on the C: drive normally on a boot disk

So I ask the people,
Is their a workaround, alternate boot loaders, way to define your own drive on an IBM/AT or even a floppy bootloader. Floppy boot disk work fine but I hate the seek time and the delay caused by it, its just not a good setup!
Also it would be great if anyone could point me to the original AT Bios setup.

Thanks
linuxsuperuser@gmail.com

[Anonymous Coward]

I had a problem similar to this trying to get a CF card going in my XT. Instead of doing a normal DOS installation using the floppy disks I used a PC DOS bootdisk, and used FDISK, FORMAT and SYS to make the drive bootable, and then manually copied all of the system files into a DOS directory. This worked on every other machine I have, but for some reason the CF card didn't like it. The only way I was able to get DOS booting was following the proper DOS installation from the floppy disks.

I remember reading an explanation for why this was so several weeks ago, but I don't have the link. Apparently when using SYS.COM program it gets confused about whether the CF card is a hard disk or a floppy disk and does something goofy. For whatever reason running the DOS setup can get around this.

If this advice was of no use, then I suggest figuring out whether your CF card is set to Fixed Disk or Removable mode. You will of course want it to be in Fixed Disk mode.

[linuxsuperuser]

I tried manually installing MS-DOS by
format C:
fdisk /MBR
sys C:
Nothing, Still "Missing Operating System"
I am going to try a copy of PC-DOS as soon as I can dig one up from the web, if anyone could provide a RAW image of disk 1 that would be great. I am wondering why PC-DOS would work over MS-DOS

As of right now, I am attempting to use a different bootloader from http://alexfru.chat.ru/eindex.html

Anonymous Coward, The CF to IDE adapter supports fixed mode only. The only jumper options are Master/Slave, 3.3/5.5vdc and laptop/regular,ext pwr IDE connectors.

Thanks

[MikeS]

I don't see why it should matter, but I notice you're both sys'ing separately instead of just format /s; might be worth a try. And you did fdisk first, right? fdisk /mbr shouldn't be necessary.

m

[Anonymous Coward]

Is there a difference between doing FORMAT and then a SYS, as opposed to FORMAT /S? I was always pretty sure FORMAT /S loaded SYS after the format was complete. Just for the record I did FORMAT /S and I still had the "missing operating system" error on boot. I'm not exactly sure why an installation with the DOS disks worked and a manual install didn't....but I spent several hours on this and that's the only way I could get it going.

I currently run PC DOS 2000, and another guy has the same hardware setup as me on his IBM PC Portable with an installation of MS DOS 6.22 I believe.

[MikeS]

No, like I said I can't see any reason why format /s and sys wouldn't work equally well, but you never know; since you were both doing the same thing and I can't think of a reason why a manual install wouldn't work it seemed like a shot.

One thing that *is* sometimes overlooked, especially when setting up multiple partitions, is making the boot partition active. But (assuming no existing partitions) Fdisk to create at least an *active* primary partition and then format /s has always worked for me.

The older versions of DOS had to have the .sys files in fixed locations at the beginning of the disk which is where format /s would presumably put them, whereas sys *might* let you put them after any existing files (like command.com perhaps) where they wouldn't be found.

All of this assumes of course that DOS is the only OS; if you are multi-booting then there are a few other issues.

Anyway, for the OP: inspect the partition table with Fdisk and make sure the primary partition is active.

The usual procedure:
1 - Fdisk to remove any existing partitions, if any
2 - Fdisk to create a primary partition *and* make it active
3 - Fdisk to create an extended & logical partitions, if any.
4 - Reset to read new partition info
5 - Format C: /s
6 - Make a directory, copy remaining files and set path, config.sys, autoexec.bat etc.

m

[Jorg]

Is the CF card being recognized/configured as a fixed disk, or as removable?

Do you have the same problem when you put a normal harddrive on the IDE port?

I'm not even sure if you should set the drive table with gsetup to 'no disk'

[linuxsuperuser]

No Luck with PC-DOS

BUT...

Setting the partition as Active seemed to be the one step I overlooked. It boots flawlessly using a 64MB CF card, Its set to see it as a 59mb HD in the BIOS but it works Okay.

Thanks!
:cool:

[genocho]

For anonymous coward:

Wich method do you use to read a cf card on a xt?

Any scsi to cf adaptor?

Tell us wich hardware you use, drivers, config.sys and all the paths to make

run a cf reader on a isa 8 bits pc xt.

Regards.

[modem7]

Apparently I can't define my Own Harddrive! I'm not sure if this is gsetup or a limitation in the AT.
It is a limitation of the IBM BIOS in the 5170.

Is their a workaround
1. Use a drive type where the cylinder count is =< cylinder count of your drive, AND head count is =< head count of your drive, AND SPT count is =< SPT count of your drive.

2. TYPE 15 in the IBM 5170 BIOS is reserved for such use. Some people in these forums have the ability to modify the BIOS to include your drive at TYPE 15. So if you have access to an EPROM programmer and a couple of 27256 EPROMs (150nS or faster), we can send you the modified BIOS code to burn to create repplacements for the IBM BIOS chips (U27/U47). Alternately, someone may be prepared (possibly for a fee to cover costs) to send you the replacement chips.

3. Replace the 5170 BIOS chips (U27/U47) with chips containing a generic AT BIOS (suitable for the 5170). Some of those generic AT BIOS' will give you the ability to define your drive in the BIOS setup. If you have access to an EPROM programmer and a couple of 27256 EPROMs (150nS or faster), you can use the AMI BIOS at http://members.dodo.com.au/~slappanel555/bios.htm Alternately, someone may be prepared (possibly for a fee to cover costs) to send you chips containing that AMI BIOS.

It boots flawlessly using a 64MB CF card, Its set to see it as a 59mb HD in the BIOS but it works Okay.
59 MB. So you've set up your IBM 5170 for a type 19 drive, which is 1024 cylinders / 7 heads / 17 SPT.

According to a web site, a type I 64MB CF unit presents as 978 cylinders / 4 heads / 32 SPT.
If your CF unit matches that, then I can see you having problems later: DOS thinks your hard drive has 1024 cylinders and will get an error when it tries to read/write past cylinder 978. DOS also thinks that your hard drive has 7 heads and will get an error when it tries to read/write to heads past 4.

Unfortunately, when I look at the drive types available in the IBM 5170, the only ones where the cylinder count is 978 or less, AND the head count is 4 or less, are 20 MB or less in size.