When you power on your PlayStation, there are two security checks that occur, referred to as 'startup queries.' The first startup query concerns regional coding on the PlayStation in relation to the regional coding on the game that is being booted. The PlayStation checks the game in order to ensure that the regional coding of the PlayStation matches the regional coding of the game. If the region codes do not match, then the PlayStation halts the boot process. For example, this is why you cannot play a Japanese game on a USA PlayStation (without a ModChip that is!). A ModChip has the ability to provide the PlayStation with a positive response to its startup regional queries, telling the PlayStation that the regional code of the game does indeed match the regional coding of the PlayStation. Therefore, a PlayStation with a ModChip installed, has the ability to play games that are encoded with different regional coding than that of the actual PlayStation. This explains how you can play import games on your domestic PlayStation.

Furthermore, each original PlayStation disk contains a section of ‘bad blocks’ that can only be written to CDROM's by technology exclusive to Sony and its game developers. When you power on the PlayStation, it queries the game disk in the system to ensure that it does indeed contain this section of 'bad blocks'. If the section of ‘bad blocks’ is detected, then the boot process continues and the game begins. If this section of ‘bad blocks’ is not detected, then the boot process is halted. When you make a CDR backup copy of a PlayStation game, there is no way to duplicate or write the section of ‘bad blocks’ on or to the CDR media. This is why a CDR backup copy of a PlayStation game cannot be played in a PlayStation, without a ModChip.

The ModChip has the ability to give the PlayStation a positive response to its startup query regarding sections of 'bad blocks.' The PlayStation is led to believe that the game in the system does contain the 'bad block' section, even though it does not. This is how CDR backup copies are made playable in a PlayStation with a ModChip. This all worked fine until protected games (also referred to as anti-mod games) were developed, requiring the need for game patches.

Protected games have two distinct software features, which can detect CDR backup copies and modified PlayStation consoles. The first feature concerns the ‘bad block’ section we mentioned earlier. The protected game seeks to confirm that the ‘bad block’ section does exist, the same way it did at system startup. In the initial anti-mod games this query was run at a fixed time interval therefore it was predictable. Conventional ModChips could accommodate this query because once a PlayStation system modified with a conventional ModChip is powered on, the ModChip continuously injects the false positive ‘bad block’ section confirmation code into the system. Therefore a conventional ModChip could overcome the first of two anti-mod detection features.

The real stumbling block for the conventional ModChip was the second anti-mod detection feature. This component of anti-mod games actually detects the conventional ModChips’ constant, false positive code transmission. Once the anti-mod game discovered that there was a device in the PlayStation, which was feeding code to the system at an inappropriate time, the game was halted and a screen displayed a warning that your system may have been modified.

A solution was quickly discovered for this new breed of anti-mod games, it was known as the Stealth ModChip. The first generation of Stealth ModChips worked like a charm on all of the anti-mod games available at the time. These games included Dino Crisis, Poporouge and Tomba2. The Stealth ModChip worked by providing the system with the appropriate code at the appropriate fixed time intervals. Then the Stealth ModChip went to sleep, or in other words it ceased its false positive code transmission. Well if you haven’t figured it out yet the key term leading to the failure of the first generation Stealth ModChip is ‘fixed time interval’. Shortly following the release of the Stealth ModChip anti-mod games began to appear which used random and multiple time intervals for its queries. ModChip dealers scrambled to adjust their Stealth ModChip code to accommodate the timing of each new anti-mod game released many releasing version 5.0, 6.0 and even 7.0 of their Stealth ModChip.