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controls:nes_snes_controller [2007/06/30 09:16]
127.0.0.1 external edit
controls:nes_snes_controller [2009/06/12 02:21]
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  ​There'​s not much to it. The 4021 IC is an 8-channel parallel to serial convertor. Every time the P/S line is switched on, the IC '​loads'​ each of the inputs. It makes each one a single '​bit'​ - 0 if not pressed, 1 if pressed. Every time the '​clock'​ line pulses, the IC shifts one bit out the serial output line.  ​There'​s not much to it. The 4021 IC is an 8-channel parallel to serial convertor. Every time the P/S line is switched on, the IC '​loads'​ each of the inputs. It makes each one a single '​bit'​ - 0 if not pressed, 1 if pressed. Every time the '​clock'​ line pulses, the IC shifts one bit out the serial output line.
  
-This about it this way: The NES is constantly outputting a '​clock'​ signal - a pulse of electricity switching between on and off very rapidly. Every time the NES wants to know what buttons are being pressed, it briefly activates the '​P/​S'​ line (think of it as a '​load'​ line) causing the 2014 to '​load'​ each button as one bit.+This about it this way: The NES is constantly outputting a '​clock'​ signal - a pulse of electricity switching between on and off very rapidly. Every time the NES wants to know what buttons are being pressed, it briefly activates the '​P/​S'​ line (think of it as a '​load'​ line) causing the 4021 to '​load'​ each button as one bit.
  
-If you imagine the inside of the 2014 as a conveyor belt, it's just placed each '​bit'​ (A 1 or 0) onto the belt, each in it's own little pocket on the belt. The '​load'​ line turns off, and the conveyor belt moves in time to the '​clock'​ signal. Every time the clock '​pulses'​ the conveyor belt moves one bit over, and shoves the next bit out the serial line. When all the bits are gone, the NES activates the load line and loads the next 8 bits onto the conveyor.+If you imagine the inside of the 4021 as a conveyor belt, it's just placed each '​bit'​ (A 1 or 0) onto the belt, each in it's own little pocket on the belt. The '​load'​ line turns off, and the conveyor belt moves in time to the '​clock'​ signal. Every time the clock '​pulses'​ the conveyor belt moves one bit over, and shoves the next bit out the serial line. When all the bits are gone, the NES activates the load line and loads the next 8 bits onto the conveyor.
  
-There'​s only one more step to this with the SNES controller. As you can see below, there are two chips. One line of the 2014 is a serial input. Imagine two conveyor belts hooked together - the bottom chip shoves the bits into the end of the first one, making one long 16-bit conveyor belt. The SNES activates the '​load'​ line every sixteen bits and then waits while the '​clock'​ line shifts the conveyor 16-bits along. Once all sixteen bits are received, the load line is activated again, and the bits are reloaded onto the belt. +There'​s only one more step to this with the SNES controller. As you can see below, there are two chips. One line of the 4021 is a serial input. Imagine two conveyor belts hooked together - the bottom chip shoves the bits into the end of the first one, making one long 16-bit conveyor belt. The SNES activates the '​load'​ line every sixteen bits and then waits while the '​clock'​ line shifts the conveyor 16-bits along. Once all sixteen bits are received, the load line is activated again, and the bits are reloaded onto the belt. 
  
 {{http://​www.gamesx.com/​grafx/​snesnesicschem.gif}} {{http://​www.gamesx.com/​grafx/​snesnesicschem.gif}}
 
 controls/nes_snes_controller.txt ยท Last modified: 2009/06/12 02:21 (external edit)
 
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