Magnetic Image Joystick interface

Arc/RPCs, peripherals, RISCOS operating system & ARM kit eg GP2x, BeagleBoard
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Magnetic Image Joystick interface

Postby sirbod » Wed Apr 04, 2018 1:32 pm

Does anyone have any details on this Joystick interface. Spheres of Chaos supports it and from looking at its code, the interface uses the Acorn Joystick SWI block &43F40. SWI &43F41 appears to return a pointer to a table of at least four words, I need the detail around what this table contains. Taking a guess:

R0+0 - ? (not used by Spheres of Chaos)
R0+4 - number of Joysticks
R0+8 - X Axis mapping?
R0+12 - ? (not used by Spheres of Chaos)
R0+16 - Y Axis mapping?

Spheres of Chaos contains the following advert about the interface and as far as I'm aware, is the only game that support it:
Magnetic Image Joystick advert.jpg

As far as I know, Mythology which is mentioned in the advert, was never released.

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Joined: Sun Aug 14, 2016 7:59 pm

Re: Magnetic Image Joystick interface

Postby hubersn » Thu May 17, 2018 5:00 pm

Never heard of the Magnetic Image interface (how was it connected to the Arc?), but I remember playing Spheres of Chaos with a Joystick interface called "Gamer's Upgrade" which was created by IOC in Germany, software was done by Matthias Seifert (author of Rockfall). It was connected to I2C, so it had to be soldered (but all other hardware expansion ports were still available!), and it was best to send your machine to IOC to fit it along with the four 9pin Atari-style connectors (e.g. on the A3000, they were fitted two-a-side right under the keyboard).

"Gamer's Upgrade" had a variety of modules coming with it, one providing Acorn joystick compatible SWIs, and one to emulate keyboard presses when moving the Joystick (worked e.g. fine for Conquerer). I don't remember which was used to interface to Spheres of Chaos.