Monday, July 6, 2015

Nintendo's Vs. System - Just Like at Home?

Vs. System Upright Version
In the year following the 1983 release of the Famicom, Nintendo began making the Vs. System arcade cabinets.  These cabinets essentially bolted two monitors with a pair of joysticks for each monitor.  The cabinet came in an upgright version with monitors at 45 degree angles to each other and a smaller sit down version with back-to-back monitors.  The Vs. System could play one game for each monitor or play a Dual System game where the game occupied both monitors.  Eventually Nintendo released a single monitor cabinet, the Vs Unisystem, which allowed for a cheaper machine which would only play one game.  You could also buy a conversion kit for some of Nintendo's older arcade stand-alone games : Donkey Kong, Donkey Kong Jr., Donkey Kong 3, Popeye and Mario Bros.  Like these games, the Vs. System board uses inverted voltages to drive the monitors.

All games confirmed to have been released in the Vs. System format were also released for the NES or the Famicom.  Typically, the Vs. System games are significantly more challenging than the home console versions.  Nintendo and its third parties had to do something to distinguish these versions from the home console versions and get people to continue to put quarters in the machines.  If they had already mastered the game at home, the arcade machines' coin boxes would not be full.

Vs. System Sit Down Version

All the Vs. System cabinets with dual monitors had a large PCB with a pair of PPUs and a pair of CPUs.  Each CPU/PPU pair had access to a set of sockets where the game code and graphics would be stored. Hardware wise, Vs. System games were almost always supplied on EPROMs.  This made them incredibly easy to copy, so Nintendo typically shipped drop-in replacement PPU chips with the games.  The Vs. System board came with four PRG sockets and two CHR sockets, each holding an 8KB EPROM.  Most earlier Vs. System Board games had 32KB PRG and 16KB CHR whereas some of their home console counterparts had only 16KB PRG and none had more than 8KB CHR.  In other words, the Vs. System board has built-in bankswitching.  This allowed for many Vs. System games to have more impressive graphics than the home console versions.  Many also have extra RAM available which the cartridge versions did not have.  Some more advanced games required daughterboards with extra memory mapping hardware to run.  Vs. Gumshoe may require a board modification.

Dual monitor Vs. System units had, for each monitor, a pair of joysticks, each with a corresponding A and B button.  Each side also had four game select buttons numbered 1-4.  These buttons were colored blue, green, purple and yellow.  On a NES controller, they correspond to player 1 start, player 2 start, player 1 select and player 2 select.  Some Vs. System games have reverse inputs, so the joystick we typically associate with player 2 (the right one) become that used by player 1. 

Vs. Unisystem
All games use RGB capable PPUs.  Some use the standard 2C03 PPU, which has a palette similar to a 2C02 minus a pair of grays and does not handle color emphasis in the same manner.  Many use one of the four 2C04 PPUs.  These PPUs function just like the 2C03 except that each of the four versions has a scrambled palette entry table.  If you use the wrong PPU with a Vs. Game, you will get colors that will look bizarre or missing.  Finally, there are four games that use the 2C05 PPU.  This has the same palette entries as a 2C03 but swaps two of the registers and uses four bits of a third register to tell the game what it is.  The game will fail if it does not have the right variety of 2C05, and there were four of these as well.  (Actually, the Famicom Titler uses a 2C05-99, but this revision does not have the swapped registers because someone used it to mod a Sharp Twin Famicom, which uses a regular 2C02G-0 PPU.)

Here is a list of known, confirmed 36 unique Vs. System games :

Game Title Compatible PPU  Notable Feature NES/Famicom Title
Atari RBI Baseball2C03/2C04-01-04 Protection IC RBI Baseball/Pro Yakyuu Family Stadium
Battle City2C04-01-04
Battle City (Famicom only)
Clu Clu Land 2C04-04
Clu Clu Land
Dr. Mario 2C04-03
Dr. Mario
Duck Hunt 2C03 Light Gun Duck Hunt
Excitebike 2C04-03
Excitebike
Excitebike  (Japan)2C04-04
Excitebike
Freedom Force 2C04-01 Light Gun Freedom Force (NES only)
Ice Climber 2C04-04
Ice Climber
Ice Climber (Japan)2C04-04 Dual System Ice Climber
Mach Rider (Endurance Course) 2C04-02
Mach Rider
Mach Rider (Fighting Course) 2C04-01
Mach Rider
Mighty Bomb Jack (Japan) 2C05-02
Mighty Bomb Jack
Ninja Jajamaru-kun (Japan) 2C05-01
Ninja Jajamaru-kun (Famicom only)
Pinball  2C04-01
Pinball
Pinball (Japan)2C03
Pinball
Platoon2C04-01
Platoon (NES only)
Raid on Bungeling Bay2C04-02 "Dual System" Raid on Bungeling Bay
Soccer  2C04-03
Soccer
Soccer (Japan)2C04-02
Soccer
Star Luster 2C03/2C04-01/02
Star Luster (Famicom only)
Stroke and Match Golf (Ladies Version) 2C04-02
Golf
Stroke and Match Golf (Men's Version) 2C04-02
Golf
Stroke and Match Golf (Men's Version) (Japan) 2C03
Golf
Super Sky Kid2C03/2C04-01-02
Sky Kid
Super Xevious - Gump no Nazo2C04-01-04 Protection IC Super Xevious - Gump no Nazo
Tetris 2C03/2C04-01-04
Tetris (Tengen)
Vs. Balloon Fight2C04-03 Dual System Balloon Fight
Vs. Baseball 2C04-01 Dual System Baseball
Vs. Baseball (Japan)2C04-01 Dual System Baseball
Vs. Castlevania2C04-02
Castlevania/Akumajou Dracula
Vs. Gumshoe  2C05-03 Light Gun Gumshoe (NES only)
Vs. Hogan's Alley2C04-01 Light Gun Hogan's Alley
Vs. Mahjong2C03 Dual System Mahjong (Famicom only)
Vs. Slalom 2C04-02
Slalom (NES only)
Vs. Super Mario Bros.2C04-04
Super Mario Bros.
Vs. Tennis 2C03 Dual System Tennis
Vs. The Goonies2C04-03
The Goonies (Famicom only)
Vs. TKO Boxing2C03/2C04-03 Protection IC Ring King/Family Boxing
Vs. Top Gun2C05-04
Top Gun
Vs. Wrecking Crew2C04-02 Dual System Wrecking Crew

As you may note from the above table, some of the third party games, essentially anything that Namco had a hand in, could use more than one PPU via dipswitches.  The correct settings of the dipswitches have been somewhat difficult to find, but thanks to a fork of Nintendulator (NewRisingSun version) I was able to get the right values for each game.  From the few Vs System manuals I was able to view the defaults appear for all dipswitches to be Off.  Here are the correct values when a dipswitch is On :

Game Name All Dips Off Dip 6 Dip 7 Dip 8 Dip 6 + 7 Dip 7+ 8 Dip 6 + 8 Dip 6 + 7 + 8
Vs. Atari R.B.I. Baseball 2C04-01 2C03 2C04-02 2C04-03 2C03 2C04-04 2C03 2C03
Vs. Battle City 2C04-01 Not Used 2C04-02 2C04-03 Not Used 2C04-04 Not Used Not Used
Vs. Star Luster 2C03 2C04-01 2C03 Not Used 2C04-02 Not Used Not Used Not Used
Vs. Super SkyKid 2C04-01 2C03 2C04-02 2C04-03 2C03 2C04-04 2C03 2C03
Vs. Super Xevious 2C04-01 Not Used 2C04-02 2C04-03 Not Used 2C04-04 Not Used Not Used
Vs. Tetris 2C04-01 2C03 2C04-02 2C04-03 2C03 2C04-04 2C03 2C03
Vs. TKO Boxing 2C04-03 2C03 Not Used Not Used Not Used Not Used Not Used Not Used

Some notable features of these games are that Vs. Super Mario Bros. uses levels from Super Mario Bros. 2 for the Famicom Disk System game for some extra challenge.  Ice Climber is perhaps the only game that came in a Dual System and a non-Dual System version.  The graphics for Tetris are much less detailed than the cartridge version Tengen released.  Mach Rider, the Fighting Course version, has the slowly revealing photo arguably showing Mach Rider to be a woman.  See here : http://nerdlypleasures.blogspot.com/2014/12/nes-female-protagonists.html  Because the revisionless 2A03 is used as the CPU, Balloon Fight will have some slight sound differences in the noise channel compared with the home console version when played on most Famicoms and all NESes.  In Duck Hunt you can shoot the dog in the bonus rounds, but that ends the round early.



The most interesting games of the bunch are the six Vs. Dual System games.  These games monopolize both monitors and the arcade PCB.  The game would utilize both CPU/PPU pairs to drive the monitors.  The two sets were able to communicate with each other a shared bus.  Some of the better NES emulators can emulate most Vs. System games but always protest when Vs. Dual System games are trying to be played. MAME is the best way I know of to play them.  Getting this co-processing system in place had to have required a great deal of work on the part of the programmers.  The Vs. Dual System games probably were not particularly popular because they used both monitors and did not work in the single monitor systems.  Raid on Bungeling Bay also requires the 2nd CPU of the Vs. Dual System but does not function like a Vs. Dual System game.


Using Vs. Balloon Fight as an example. you can play with two players in two modes.  In the first mode, both players are on the same screen and can see each other.  They can break each other's balloon and push each other away.  Essentially you are competing for who can score the most points.  In the second mode, each player can play the game completely independently as if you were playing on two completely separate arcade machines.  The rest of the Dual System games play like this.  While you can get the same experience on a single screen, it undoubtedly felt cool to have a screen all to yourself.  


The Vs. System represented one of the last serious attempts by Nintendo to maintain an arcade presence. Most of its early home console NES games found their way to a Vs. System cabinet.  Those that did not, Donkey Kong, Donkey Kong Jr., Donkey Kong 3, Popeye and Mario Bros. already had standalone arcade versions that were superior to the NES-based Vs. System.  Most of the other early Nintendo home console games like Go, Gyromite, Stack-Up, Donkey Kong Jr. Math and Popeye English Lesson just were not suitable for an arcade machine.  Unfortunately, arcade games were continually evolving and what seemed fairly competitive in 1984 was looking positively ancient by 1987.  All but six of these games had been originally released from 1983-1986.  But for the early years Nintendo could almost always boast that their home console games were close ports of their arcade cousins.


Nintendo's own interest in unique arcade hardware was also fading.  As the NES and Famicom became more popular, Nintendo focused more on the Playchoice-10 than the Vs. System.  The Playchoice 10 was more attractive to arcade owners because they could fit ten games into a cabinet instead of two.  Which would you rather have as an arcade owner, a Playchoice 10 or essentially a Playchoice 2?  Also, they did not have to plug EPROMs into sockets, they only had to plug boards into a Playchoice 10 PCB.  Game developers could ship their games on a Playchoice-10 board with virtually no changes, whereas a fair amount of work was required for a Vs. System conversion.  Thereafter, the Nintendo Super System was the equivalent of the Playchoice-10 for the SNES and much later it released a few games for the Seta Aleck64 and the Nintendo Triforce System, which are essentially N64 and Gamecube hardware in arcade machines.  Oddly enough, Nintendo did manufacture the arcade hardware for the Irem-developed classic R-Type, but by the time of the Vs System its adventures in arcade hardware were almost over.

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