 The magazine of the Melbourne PC User Group Copying Disks of Different Size Tom Coleman |
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D1SKCOPY makes a sector by sector copy of the data on a disk and can run into all kinds of problems doing that. For example, if the Target Disk has a bad area or bad sectors DISKCOPY will insist on writing to them if the Source Disk has data in that location. The result is frequently an error message, "Bad Write".
Disks with odd sized or missing sectors always fail, too. These disks are usually interfered with by the manufacturers as a form of copy protection.
If the source disk has a bad sector then DISKCOPY faithfully makes a bad sector in the same place on the target, regardless of the condition of the media.
Some copy techniques, usually associated with the machinery that makes the copy, will only format the tracks containing data. It saves time copying by missing out blank tracks. That causes mass confusion to DISKCOPY
Generally speaking, you can only DISKCOPY from and to identical disks, but there is a technique to DISKCOPY from a 5.25-inch to a 3.5-inch under some circumstances.
It applies to only those of us who are using a 3.5-inch and a 5.25-inch drive using the same controller card. It will also be more successful on XTs than ATs.
Generally, if you are using one controller card, the card sees both disks as being the same and you must add DEVICE=DRIVER.SYS /D:1 (or some other parameters, depending on drive and desired size) to CONFIG.SYS to get it to see the drive as a different size.
By removing the DRIVER.SYS line from CONFIG.SYS the computer thinks both disks are the same size and DISKCOPY works just fine.
You finish up with a 360 kB, 3.5-inch disk with 40 tracks and 9 sectors per track and which will run in any other 3.5-inch drive.
If you have an AT or 386 the drive type is specified in CMOS and is read at boot up. To avoid an error message make the drive size NOT INSTALLED. If that does not work, then this method may not work for you.
The technique works well between 360 kB and 720 kB disks and I understand that, with a bit of luck, it will work between 1.2 MB and 1.44 MB disks.
I have not tried, but it should work from a RAM Disk provided the disk has the correct sectors and tracks.
Have a go. It gives you a feeling of omnipotence making DOS do things it was not intended to do. It's a mental raspberry to the people who inflicted DOS on us.
Reprinted from the September 1993 issue of PC Update, the magazine of Melbourne PC User Group, Australia
