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[AQUARIUS] mini-expander controller ports

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Does any one know if the Aquarius mini-expander ports work with any other controller for example Intellivision controllers? jaybird3rd has mentioned the possibility of a miniexpander II so it would be interesting to know what the options are




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As it happens, I've been looking at various ways of interfacing other controllers to the Aquarius, including Atari controllers. Let me share what I've discovered so far.


Much like the Intellivision, the Aquarius hand controller ports are connected directly to the two parallel I/O ports provided by the AY-3-8910. The left controller port (used by "Player 1") is assigned to Port A, and the right controller port (the one closest to the outside edge of the Mini Expander, used by "Player 2") is assigned to Port B. The Aquarius and Intellivision hand controllers are also similar in that they generate Gray codes for each of the possible disc directions and key combinations. Unfortunately, the Intellivision and Aquarius hand controllers are wired differently, and the codes generated by both controllers are somewhat different, so making full use of an Intellivision controller isn't simply a matter of building a passive adapter.


Deathskull Laboratories has a nice breakdown of the Intellivision hand controller interface, including pinouts and Gray code tables. Here is a corresponding table for the Aquarius:





(P1 through P16 are the disc directions, as indicated in the above diagram, and K1 through K6 are the hand controller keys 1 through 6.)


If you compare the codes for the Intellivision and Aquarius hand controllers, you'll notice that the direction discs on both controllers generate the same codes; only the pin assignment is different. I haven't tried this myself yet (I'll edit this post when I do), but it looks as though you can interface the Intellivision hand controller to the Aquarius, and at least use the direction disc, by connecting the pins in the following way:


====     ========
 01         06
 02         07
 03         08
 04         09
 05         01 (GND)
 09         05

This provides the Aquarius with the five bits that are needed for the disc. The remaining three are used by the six hand controller keys, but unfortunately, the Gray codes for these keys don't agree very well with the codes used by the Intellivision keypad and action buttons. So, if you want to be able to plug in an Intellivision II controller, and have the Intellivision keys mapped to the Aquarius keys so that Aquarius software can use them without modification, it would probably require a more sophisticated adapter.


However, it wouldn't be difficult to build a simpler adapter for new Aquarius games programmed specifically for the Intellivision II controller; the games would simply have to decode the Intellivision and Aquarius keypad inputs differently. With a different pinout, it would even be possible to interface the Intellivision Flashback controller to the Aquarius also.

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Fortunately, interfacing an Atari CX-40 (or compatible) joystick is easier. The CX-40 is an exceedingly simple controller: each of the four joystick directions and the action button are assigned to a pin, and when you press a direction and/or the button, the CX-40 forces the corresponding pin(s) low. That matches nicely to the corresponding inputs on the Aquarius hand controller: look again at the chart above, and notice that for each of the four main disc directions (Up/P13, Down/P5, Left/P9, and Right/P1) and for K1, only one pin needs to be forced low.


So, if you want to interface an Atari joystick to the Aquarius, so that the stick maps to the disc and the action button maps to K1, you can build a simple adapter which connects the CX-40 pins to the hand controller port's pins in the following way:


=====     ========
  1        7 (P13/UP)
  2        9 (P5/DN)
  3        6 (P9/LT)
  4        8 (P1/RT)
  6        3 (K1)
  8        1 (GND)

I tried this just a moment ago on my Aquarius, just to make sure that it would work, and it happens to work very well. It even corresponds nicely to the diagonals, even though the Atari joystick diagonals don't line up perfectly with the Aquarius diagonals: referring to the Aquarius disc diagram in the previous post, U/R on the Atari joystick maps to P16 rather than P15, U/L maps to P12 rather than P11, D/R maps to P4 rather than P3, and D/L maps to P8 rather than P7. Fortunately, the Aquarius games that make use of the directionals seem to properly decode the sixteen-direction disc so that these "inbetween" diagonals are accepted. I tried it successfully with Snafu and TRON Deadly Discs, and I'm sure it would work with other games as well.


So, for the Mini Expander alternatives that I'm working on, I'm thinking of a few different ways of accommodating Atari controllers. For the internal Mini Expander upgrade, I'll probably keep it simple and give you the option of rewiring the hand controller ports (which will be a set of breakout cables that feed into the back of the Aquarius) for Atari joysticks—or, for that matter, for Intellivision II and Intellivision Flashback controllers. With the Mini Expander II, I'd like to add two dedicated Atari ports, interfaced to the second PSG, which will support up to two Atari joysticks or four Atari paddles. These won't be backward-compatible with the (unmodified) original Aquarius games, but they will open up the Aquarius to paddle games and to four-player games, which will be exciting. The "Atari adapter" that I describe above will also work with the regular hand controller inputs in the Mini Expander II.

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