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This article has multiple issues. Please help improve it or discuss these issues on the crack для Perfect Disk page. This article possibly contains original research.
Please improve it by verifying the claims made and adding inline citations. Statements consisting only of original research should be removed. This article needs additional citations for verification.
Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. A crack refers to the means of achieving software cracking, for example a stolen serial number or a tool that performs that act of cracking.
Some of these tools are called keygen, patch, or loader. A keygen is a handmade product serial number generator that often offers the ability to generate working serial numbers in your own name. A patch is a small computer program that modifies the machine code of another program.
This has the advantage for a cracker to not include a large executable in a release when only a few bytes are changed. A loader modifies the startup flow of a program and does not remove the protection but circumvents it.
A well-known example of a loader is a trainer used to cheat in games. Fairlight pointed out in one of their . A nukewar has shown that the protection may not kick in at any point for it to be a valid crack.
Обзор на «Crack для Perfect Disk»
- The distribution of cracked copies is illegal in most countries.
- There have been lawsuits over cracking software.
- It might be legal to use cracked software in certain circumstances.
- Educational resources for reverse engineering and software cracking are, however, legal and available in the form of Crackme programs.
- The first software copy protection was applied to software for the Apple II, Atari 800, and Commodore 64 computers.
- Software publishers have implemented increasingly complex methods in an effort to stop unauthorized copying of software.
On the Apple II, unlike modern computers that use standardized device drivers to manage device communications, the operating system directly controlled the step crack that moves the floppy disk head, and also directly interpreted the raw data, called nibbles, read from each track to identify perfect data sectors. In addition, tracks did not need to be perfect rings, but could be sectioned so that sectors could be staggered across overlapping offset tracks, the most extreme version being known для spiral tracking.
It was also discovered that many floppy drives did not have a fixed upper limit to head movement, and it was sometimes possible to write an additional 36th track above the normal 35 tracks. The standard Apple II copy programs could not read such protected floppy disks, since the standard DOS assumed that all disks had a uniform 35-track, 13- or 16-sector layout. Apple II copy program could read. One of the primary routes to hacking these early copy protections was to run a program that simulates the normal CPU operation.
The Apple II provided a built-in opcode disassembler, allowing raw memory to be decoded into CPU opcodes, and this would be utilized to examine what the copy-protection was about to do next. Generally there was little to no defense available to the copy protection system, since all its secrets are made visible through the simulation. However, because the simulation itself must run on the original CPU, in addition to the software being hacked, the simulation would often run extremely slowly even at maximum speed. On Atari 8-bit computers, the most common protection method was via «bad sectors».
These were sectors on the disk that were intentionally unreadable by the disk drive. The software would look for these sectors when the program was loading and would stop loading if an error code was not returned when accessing these sectors.
Special copy programs were available that would copy the disk and remember any bad sectors. The user could then use an application to spin the drive by constantly reading a single sector and crack для Perfect Disk the drive RPM.
With the disk drive top removed a small screwdriver could be used to slow the drive RPM below a certain point. Once the drive was slowed down the application could then go and write «bad sectors» where needed. When done the drive RPM was sped up back to normal and an uncracked copy was made. Of course cracking the software to expect good sectors made for readily copied disks without the need to meddle with the disk drive.
As time went on more sophisticated methods were developed, but almost all involved some form of malformed disk data, such as a sector that might return different data on separate accesses due to bad data alignment. BIOS in Atari’s «smart» drives. These upgraded drives allowed the user to make exact copies of the original program with copy protections in place on the new disk. On the Commodore 64, several methods were used to protect software.
For software distributed on ROM cartridges, subroutines were included which attempted to write over the program code. If the software was on ROM, nothing would happen, but if the software had been moved to RAM, the software would be disabled. Because of the operation of Commodore floppy drives, one write protection scheme would cause the floppy drive head to bang against the end of its rail, which could cause the drive head to become misaligned.
In some cases, cracked versions of software were desirable to avoid this result. A misaligned drive head was rare usually fixing itself by smashing against the rail stops. Another brutal protection scheme was grinding from track 1 to 40 and back a few times.
Most of the early software crackers were computer hobbyists who often formed groups that competed against each other in the cracking and spreading of software. Breaking a new copy protection scheme as quickly as possible was often regarded as an opportunity to demonstrate one’s technical superiority rather than a possibility of money-making. Some low skilled hobbyists would take already cracked software and edit various unencrypted strings of text in it to change messages a game would tell a game player, often something considered vulgar.