Disk Copyguarding

 

The very first form of software protection came in 1979. Before that people could just copy a disk with DOS using the 'J' option. They were free to copy and duplicate any disk they could get their hands on.

Then the first copyguards appeared. People were shocked when they duplicated a disk and it did not work. They would sit and copy a disk a dozen times, almost endlessly, only to find out that when they went to run the program that they probably thought they had copied it would not run or something was missing. What they did not realize at first was that some of the programs that they had copied were actually not being copied. What they would end up with was a few missing sectors from the original program!

What the software manufacturers would do is go to sector 360 (the Bit Map) and take some of the sectors that were marked in use with "F's" and simply mark them with "0" (zero). Now as we discussed earlier that when you 'J' a disk or duplicate it the first thing DOS will do is to check the Bit Map to determine how many sectors it must copy. So when the disk was duplicated sectors vital to the program would not be reproduced. In other words the first copyguards would fool DOS into thinking certain sectors were not in use when indeed they were needed.

It did not take the (so-called) code crackers long to figure this out when they examined the disk. They would see that things were not quite right in the Bit Map. Usually they would fool around and keep marking sectors not in use as sectors in use until they were able to make a working copy of the disk.

You may want to experiment with this. Take a file and mark a few sectors in that file with 0 as not in use, then do a 'J' option or dup the disk with DOS. When you run the program you will find it will not run because there are what you call missing sectors. You may want to use this form of protection for some of your own software.

To defeat this form of protection the first software copy programs appeared on the market. We will not go into the moral aspects of these copy programs here.

The most famous and controversial of these copy programs was called "SUPER-DUP." SUPER-DUP was DOS with the 'J' option: DUPLICATE DISK MODIFIED.

Back then people were amazed with the magic of SUPER-DUP. They were able to copy virtually any disk yet they could not do it with regular DOS. SUPER-DUP DOS spread throughout the country. It is now the standard DOS which all people use just in case there is a sector on the disk that is marked not in use when it is needed by the program.

People ask how does SUPER-DUP copy these disks when DOS will not? It is amazing how something as powerful as SUPER-DUP can be so simple in operation. This is how it works. SUPER-DUP will simply copy _all_ of the sectors on a disk from 1 to 720. It will ignore the Bit Map and does not care which sectors are marked in use. SUPER-DUP would take a little more time to duplicate a disk but the disk that it would copy would run every time.

After SUPER-DUP the market was flooded with copy programs. They would sell for up to $40.00 each. People could now backup their software and they were happy. Many tricks were used by the software manufacturers like moving the Bit Map (sector 360) to another sector. It would now be hidden but whatever they did SUPER-DUP would copy the disk.

Around 1980 there was a new form of software protection to hit the marketplace. It shocked the country! All of a sudden SUPER-DUP and the other copy programs would not work. When they tried to copy a disk with this new form of protection their disk drives protested with a horrible grinding noise. Sometimes they would have to shut down their disk drives for fear of burning out their drive motors. SUPER-DUP was useless! They did not know what to do. Days and weeks were spent trying to copy the new disk. People were wondering what could be done about this and sure enough through this new form of protection

there came a new form of people that had extensive knowledge of machine language and they would devote days searching through the code of one disk. What they found was what has become known as "The Bad Sector" or what is otherwise known as "The Missing Sector." This form of copyguard is still used today although not as popular as the more modern copyguarding techniques.

From here on we will briefly cover and discuss the various copyguarding techniques used. We will go into greater detail on each one later in this book.

With the bad sector came what is now widely know and used today as "the custom formatting of the disk."

The software manufacturers soon realized that the Atari 810 disk drive had certain built-in limitations. So they made special modifications to their drives. Now they could write their software with their special modified drives and the stock 810 disk drive could not reproduce what they put on the disk.

They could write bad sectors and double sectors or put extra sectors on a disk. For example, if you were to put 19 sectors on a track with a special modified hardware enhanced drive the normal 810 disk drive would not be able to reproduce the 19 sector per track format. If you then made the copyguarded software check for the 19 sector format and if it did not find it, have the program lock up then you would have a good copyguarded disk, knowing that the unmodified 810 disk drive could not write 19 sectors per track no matter what the copy program instructed it to do.

To sum it up the copy guarded software checks to see that these bad sectors and custom format are on the disk. The bad sectoring becomes part of the program and the program checks for it to be there.