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USB vs PS/2 vs COM vs LPT
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saint:

--- Quote from: Driver-Man on September 20, 2010, 10:06:00 pm ---
--- Quote from: RandyT ---Without the pull-up resistors, the method will not work at all on parallel ports where they weren't built in.  Some were, and some weren't.

--- End quote ---

I suppose all 5 of my computers had them built in.

How do you know about it? Can you back that up, would there be some article on the Internet about it?

--- End quote ---

http://www.beyondlogic.org/parlcd/parlcd.htm

http://www.hmpg.net/pinewood/

http://hw-server.com/docs/scp_ecp.html

http://www.finitesite.com/d3jsys/

"Normally the Printer Card will have internal pull-up resistors, but as you would expect, not all will. Some may just have open collector outputs, while others may even have normal totem pole outputs. In order to make your device work correctly on as many Printer Ports as possible, you can use an external resistor as well. Should you already have an internal resistor, then it will act in Parallel with it, or if you have Totem pole outputs, the resistor will act as a load."
http://www.luberth.com/cstep/parallel.htm



:dunno - that was just a quick Google search, and not my area of expertise.


--- Quote ---No place in community? ...Driver-Man, friend or foe?


--- End quote ---

Plenty of room for someone building a better mousetrap or pushing the envelope of the hobby. Not so much room for confrontational attitudes :) You decide where you fit, I'd like to see where your contributions can take things -- mind the rules!

--- saint
RandyT:

--- Quote from: Driver-Man on September 20, 2010, 10:06:00 pm ---I said I tested this on 5 computers, pay attention.

And what if it is you "who does not know", my human friend?

I know exactly what happens, take a look at the driver source code.

--- End quote ---

Apparently you don't, and have proven my point.  It seems I gave you more of my time than I should have.  You'll have to get someone else to pay attention to you from here on out.

RandyT
Driver-Man:

--- Quote from: RandyT ---Apparently you don't, and have proven my point.

--- End quote ---

I suppose this is your point:
- "Without diodes, what do you think happens at junction [ACK, Data 0] ?"

Whatever you imagined happens, it does not happen. Can you now actually say what in the world were you hinting at? This is not some "keyboard matrix", there is no 'ghosting', or whatever is it you're being mysterious about.


As I said, what happens is described in the source code (above).... there is a loop that sends signal to each separate "ground wire" for joysticks 1 to 7, in sequence. Inside that loop you simply check if the signal has passed through any of the 9 data lines, and whichever line is set it means the microswitch circuit was closed, that's all. -- "Ground wires" are completely separate between 7 joysticks, while data lines can be shared between them all. This is completely opposite to JAMMA loom, but actual wiring is almost the same, and this is actually simpler (less wires). It's perfect.


=============
USB = ?? bits per second/11 = ?? inputs per frame @ 60 FPS
RandyT:

--- Quote from: Driver-Man on September 21, 2010, 01:32:22 am ---Whatever you imagined happens, it does not happen. Can you now actually say what in the world were you hinting at? This is not some "keyboard matrix", there is no 'ghosting', or whatever is it you're being mysterious about.

--- End quote ---

Try again.
AndyWarne:

--- Quote from: Driver-Man on September 20, 2010, 09:52:38 pm ---
--- Quote from: AndyWarne on September 20, 2010, 04:49:42 pm ---
--- Quote from: JustMichael on September 20, 2010, 03:37:34 pm ---
USB does not transmit just 1 key each time it is polled like you are trying to suggest.  The USB device transmits a block of data each time it is asked.  The computer takes the USB data and determines which keys are being press and tells Mame all the keys that are being pressed each time Mame asks.


--- End quote ---

Spot on. Furthermore the I-PAC is polled at 500Hz . There is just no issue here.

The way in which all pressed keys are sent, in virtually no time (12 Mbps), as a packet, and processed as such on the PC is the closest you will get to a game board.

--- End quote ---

You mean USB is polled at 500Hz. Do we have some reference to confirm that number?

I'm asking at what maximum rate can I-PAC *generate* scan codes, how many per second?



--- End quote ---

OK here is a USB bus analyzer trace. This is the result of pressing 5 keys at the same time. Note the 2ms time intervals, and the fact all pressed keys (5 keys) are sent together.
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