# Compaq Contura Aero 4/33C - moving data to CF/IDE disk - No operating system detected

I've got a Compaq Contura aero 4/33 laptop with original DOS system installed. As the HDD is old and dying, I've decided to copy the drive to a CF card on a CF/IDE adapter.

After connecting the drive, according to diskutil and fdisk, I can see following partition table:

/dev/disk3 (external, physical):
#:                       TYPE NAME                    SIZE       IDENTIFIER
0:     FDisk_partition_scheme                        *256.5 MB   disk3
1:                 DOS_FAT_16 NO NAME                 252.3 MB   disk3s1
2:                       0x12                         3.2 MB     disk3s3

sh-3.2# fdisk /dev/disk3
Disk: /dev/disk3    geometry: 994/8/63 [501073 sectors]
Signature: 0xAA55
Starting       Ending
#: id  cyl  hd sec -  cyl  hd sec [     start -       size]

*1: 06    9   0   1 -  719  10  63 [      6237 -     492723] DOS > 32MB
2: 00    0   0   0 -    0   0   0 [         0 -          0] unused
3: 12    0   1   1 -    8  10  63 [        63 -       6174] Compaq Diag.
4: 00    0   0   0 -    0   0   0 [         0 -          0] unused


I've made the image by dd'ing the entire drive and putting it straight on the CF disk (dd if=/dev/disk3 of=./image.bin; dd if=./image.bin of=/dev/disk4).

Fdisk'ing the CF card (1GB Kingston) shows a following partition table:

Disk: /dev/disk4    geometry: 967/32/63 [1949472 sectors]
Signature: 0xAA55
Starting       Ending
#: id  cyl  hd sec -  cyl  hd sec [     start -       size]
*1: 06    9   0   1 -  719  10  63 [      6237 -     492723] DOS > 32MB
2: 00    0   0   0 -    0   0   0 [         0 -          0] unused
3: 12    0   1   1 -    8  10  63 [        63 -       6174] Compaq Diag.
4: 00    0   0   0 -    0   0   0 [         0 -          0] unused


However, laptop does not detect any operating system. When I start it, only a "Missing operating system" message is shown.

But, when I press F10 during boot, it seems to boot up DOS with the Compaq Diagnostics tools

Trying to change Cylinders/Heads/Sectors values in this diagnostics tools to the ones provided by fdisk (geometry: 967/32/63) changes nothing, still missing operating system.

So, how can I move entire os to a new drive?

• After you clone the drive, can you see the files on the new drive? If so, have you tried running the DOS command, fdisk /mbr ? – Tim Locke Nov 13 '16 at 23:43

Because these drives have different geometries and multiple partitions, you can't dd the whole thing in one pass and expect everything to work. In particular, your DOS partitition which was located at cylinder 9, track/head 0, sector 1 on the old drive, is now located somewhere different on the new drive (which has 4 times as many tracks per cylinder as the old one).

Keep in mind, dd does not copy cylinder x, track y, sector z to cylinder x, track/head y, sector z -- it copies logical block n to logical block n, and if n on one drive is a different CHS value than the same n on another drive, that's none of dd's business. (when I say dd here it's really the Linux kernel, but same outcome).

You will have a better result if you do the following:

1. see what partitions are on the old disk.
2. make partitions on the new disk that match the old ones.
3. dd each partition separately (e.g. dd if=/dev/disk3s1 of=/dev/disk4s1, then dd if=/dev/disk3s3 of=/dev/disk4s3)

Using a single dd pass does work when your disk has only one partition which starts on the first track (or in the first cylinder, if both drives have the same number of sectors per track, e.g. 63). It also works when both drives have the same number of tracks and sectors per cylinder.

Like Ken Gober said, you can't expect to clone drives with different geometries this easily :)

Also you should make sure the BIOS recognizes the drive properly. If it's an early revision it might be limited by the 504 MB barrier (1024/16/63). Your 1GB CF exceeds those (967/32/63).

If in doubt you can use the latest BIOS (sp1992) which allows for drives up to 8.4GB without any software trick. I found this update at HP's website.

• To explain: Drives marketed after about 1999 are usually large enough that they are useless without LBA, and C/H/S geometry is always "full tilt" with all values pegged. Not so with earlier drives.... – rackandboneman Sep 17 '17 at 12:27