Here's how I did it

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: I use a hacked Gravis Gamepad for P1 controls, so I'm actually only using 14 buttons (P2 u/d/l/r, 4 buttons, p1 start, p2 start, tab, esc, #3 and #4 for coins). I actually use P2 button 4 for coins on that side (where it matters), and reassigned #4 as pause. : But this process might still work, depending on your configuration. : Firstly, you don't need to worry about ghosting issues with the admin buttons at all. These buttons aren't used simultaneously with the controls, so there is no ghosting opportunity. : Secondly, you don't need to worry about ghosting issues with opposite controls, ie: a joystick can't be in both the up and down position at the same time, so there are no ghosting issues here. Plan 'suspect' buttons in these opposite positions. : Buttons require 2 leads. I'll refer to them as the 'A' pool and the 'B' pool for the purpose of this discussion. (Once you take a KB apart, this will make sense). : What I did was to work backwards- First, I identified the leads for the admin buttons, and wired them. In hindsight, it only mattered that I wired these buttons to their defaults for AOS control (ie ESC for dumping the frontend, 1 and 2 for editing menus in AOS, enter for changing values, which joypad but 1 does by default, anyways). : Then, I identified unused leads, and got 6 additional keys, for the P2 controls. of course, I needed 2 more for a total of 8, (u/d/l/r/1/2/3/4), so I picked 2 of the 6 and used one of their 'A' leads, and an unused 'B' lead, and used these in opposition to one another for U/D/L/R. : My main goal was to reduce the amount of soldering to the KB PCB that I needed to do. From memory, I think that I only ended up needing to solder about 6 or 7 leads in each of the A and B pool, from an approximate total of 11 or 12. : In the end, I ended up with T,/,Q,P,space,7,num /, and 2 others, as the available keystrokes, and mapped mame accordingly. I determined these as I went along, simply leaving the mame key config open, and touching wires together to show what registered. : It's not pretty, since it's all hard-soldered, but it works fine. In hindsight, I understand that I might have nuked the KB controller chip on the mainboard if I got unlucky with my random testing. Fortunately, I was using an old 486/66 as my test box, so I probably wouldn't have cried all that much. : The whole thing took about 1.5 hours, but it didn't cost me a dime. : Let me know if you want to know more about this approach. : : : : Hi, I want to build a custom controller to use with Mame with 2 joysticks, each with 6 buttons, and all the admin buttons like player buttons, coin buttons etc. I believe it takes around 24 contacts in total. : : I want to take apart a old keyboard and use it as the controller, but I hear a lot about ghosting and blocking key problems. Has anyone successfully done this and any hints you can give me? Also any good links to good keyboard hack sites? : : Thanks for all your help

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