{"id":1158,"date":"2018-09-19T22:31:34","date_gmt":"2018-09-19T21:31:34","guid":{"rendered":"http:\/\/blog.blockos.org\/?p=1158"},"modified":"2018-09-20T08:15:00","modified_gmt":"2018-09-20T07:15:00","slug":"fred-astaires-doppelganger","status":"publish","type":"post","link":"https:\/\/blog.blockos.org\/?p=1158","title":{"rendered":"Fred Astaire’s Doppelg\u00e4nger"},"content":{"rendered":"\n

Oh crap… This blog is getting dusty. Anyway, let’s get started!<\/p>\n\n\n\n

I compared the Street Fighter 2 Champion Edition joypad routine with the one from\u00a0HuDK<\/a>. One of the most interesting thing is that SF2 performs an extra joyport read after reading the 5 joypad states in order to check if a Multitap (PI-PD003) is there. If the returned value is $F0<\/strong>, we have a Multitap.<\/p>\n\n\n\n

Is there a way to detect how many joypads are plugged? What about the other multitaps<\/a>?\u00a0<\/p>\n\n\n\n

Hopefully a Twin Tap and a Twin Commander magically landed on my desk for some time (thanks Adoru<\/a>).<\/p>\n\n\n\n

Let’s start with the Twin Tap. It’s a 2 ports multitap. Unfortunately there’s no way to detect available joypads or a 2 ports multitap.<\/p>\n\n\n\n

Anyway! This multitap has some interesting\u00a0peculiarity. If you check the you’ll see that there’s not 2 but 3 ports and a 3 positions selector switch. Why is there a third connector and a selector switch? I’m afraid we’ll never know.<\/p>\n\n\n\n

The selector switch changes the joypads order. This means that the joypads plugged in the Twin Tap will appeared at a different position in the joypad read routine. Here’s a table with the switch positions and the joypad “positions”.<\/p>\n\n\n\n

\n
\n
\"\"<\/a><\/figure>\n<\/div>\n\n\n\n
\n
Switch position<\/td>1<\/td>2<\/td>3<\/td><\/tr>
Joypad #0<\/td>A<\/td>C<\/td>C<\/td><\/tr>
Joypad #1<\/td>B<\/td>C<\/td>C<\/td><\/tr>
Joypad #2<\/td>C<\/td>A<\/td>C<\/td><\/tr>
Joypad #3<\/td>C<\/td>B<\/td>C<\/td><\/tr>
Joypad #4<\/td>C<\/td>C<\/td>A<\/td><\/tr><\/tbody><\/table>\n\n\n\n

<\/p>\n<\/div>\n<\/div>\n\n\n\n

As the C<\/strong> port is hidden (unless you are a sneaky hacker), the joyport value will always be $FF<\/strong>\u00a0(no buttons pressed).<\/p>\n\n\n\n

Conclusion:<\/strong> At the time of writing this post, only the Multitap (PI-PD003) can be detected and we can’t detect if a joypad is plugged. I don’t have much hope for the Joy Tap 3, the Battle Tap or the X-HE2, but who knows…<\/p>\n\n\n\n