Atari 7800 Pro System

HIDDEN MESSAGE: Written in traces on the bottom of the original pcb version are the initials “DJS” (for designer Dan J. Schwinn).

5 different models were released.  The original 5k 1984 models (built in El Paso) have an expansion port on the left side of the system, which was intended for use with a laserdisc system.  The 2nd run of systems had a revised pcb with the port omitted, although the cases still had a hole for it.  The 3rd had cases with an outline on them where the hole used to be.  The 4th and 5th run of cases had no outline.  The revised pcb in the later models includes an extra timing circuit that was added in an effort to fix an incompatibility problem with the 2600 game Dark Chambers.  Unfortunately this created some incompatibility issues with a few other 2600 games that use the FE bank-switching method (they may either work fine, the screen will roll, or they won’t work at all), such as Centipede, Decathlon, Kool-Aid Man, Millipede, Robot Tank, Space Shuttle, Time Pilot, and the Supercharger (this will only work on the original 1984 model), as well as 7800 Food Fight.

Originally Pole Position II was to be built-in, according to a 1984 Electronics Games article.  Later PAL models have Asteroids built-in. 

1st game console to incorporate a way to lock out unauthorized 3rd-party games.  The lockout was even cryptographic and impossible to break for years after its release w/o modifying the console.

PAL systems don’t have a channel switch on the back.

Some 7800 consoles have an additional chip on the board that pulls down the address lines in the middle of the cycle. This issue only exists on some PAL consoles and very few NTSC consoles (if any).

There’s a difference with how RAM is handled (i.e. where it’s mapped) on this system, compared to the original VCS/2600 models.  Mountain King is a perfect example of how the game isn’t exactly the same, as apparently you can’t reach the Secret Kingdom.  {John Harvey}

RUMOR: Several hundred systems were made with power and/or pause switches that worked backwards.


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