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| Marsupial:
--- Quote from: MonMotha on September 22, 2010, 01:16:04 pm ---Just to be clear, the IO circuits on old-school arcade boards are effectively multiplexing the inputs in (usually) 8 at a time. Multiple parallel ports would do the same thing. Each group of 8 bits would hang off the data bus and be read at different addresses via the use of tri-state buffers gated by the the decoded low order address bits (74244 or similar gated by a 74138 or similar). Using several parallel ports just causes the sets of data (still only up to 8 at a time - the data lines and status lines are in separate 8-bit registers). Adding an external mux driven off the parallel port control lines or using a register system is really no different than how authentic hardware did it. You still have full control over exactly when everything is sampled. --- End quote --- regardless, the point is, even with parallel ports you don't get the "same result" as you have the emulation software doing the job of polling the buttons. But thanks for clarification; I haven't looked a lot on arcade PCBs. |
| DJ_Izumi:
--- Quote from: JustMichael on September 22, 2010, 06:48:24 pm ---Thanks!! I had no idea that was why the USB keyboards I have tried all have the same 6 key limit. :applaud: --- End quote --- Cheap encoders on the keyboard. I've seen some jam when you press more than three even. Really depends on the quality of the keyboard encoder. Of course obviously in most NORMAL cases a keyboard won't have you pressing more than 6 buttons ever. |
| Driver-Man:
--- Quote from: JustMichael ---When a pin is set to 0 that IS ground. You are using pins 2, 3, 4 as outputs so they are either output a 1 (power) or a 0 (ground). 18-25 are just always ground (a 0). --- End quote --- Yes, they are either 0 or 1. Active "ground" line is actually set to 1, but there is 'active low' and 'active high', for example bit 7 happens to show logic 0 where there actually is +5v at pin 11. --- Quote ---Below is a picture of what I think you are trying to do. This is a matrix. --- End quote --- Do you know better than me what I had for breakfast too? http://www2.burg-halle.de/~schwenke/parport3.html --- Code: --- |---[/]........................ pin 10 (left) | . |---[/]........................ pin 11 (right) | . . | |---[/]..... . | | . | |---[/]......... | | | | | | | ------------------------------ pin 3 (ground 2) | |-------------------------------- pin 2 (ground 1) --- End code --- Matrix? Do not try and bend the spoon. That's impossible. Instead... only try to realize the truth. - I am not trying to do anything, I already did it. Wake up, Neo. |
| RandyT:
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| Driver-Man:
MonMotha, I like your super-powers, most impressive. Do you know what is actual, or most likely, bottleneck in the whole story with USB and keyboard controller, and how many scan codes per second that comes down to? Do you know at what rate PS2 DualShock and clones can generate data, and if that thing is plugged via PC USB what would set the bottleneck then? |
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