Amiga.org
Amiga computer related discussion => General chat about Amiga topics => Topic started by: ElPolloDiabl on July 05, 2013, 02:19:46 PM
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A couple years back there was quite a long argument about joystick polling speed.
I have found an answer at: http://pinouts.ru/Inputs/GameportPC_pinout.shtml (http://pinouts.ru/Inputs/GameportPC_pinout.shtml)
If you read paragraph two: The joystick interface card was designed to be as simple and cheap as possible. The card consisted only of bus interface electronics and four monostable multivibrators (all in on 558 chip). Those monostable multivibrators were simple timer circuits which put out a pulse with width directly proportional to the joystick resistance value. The pulse width was then measured using software loop. This has caused anormous amounts of problems to game programmers when computers have become faster and faster all the time. On faster machines, the joystick routine in the software does not read the joystick signal properly resulting in a timing problems. Some dedicated joystick cards are designed to vary the joystick signal so the software can properly detect the joystick and process the data.
Whereas the Atari/Amiga style is a fairly simple design and wouldn't get any timing issues.
Link here: http://old.pinouts.ru/Inputs/JoystickAtari2600_pinout.shtml (http://old.pinouts.ru/Inputs/JoystickAtari2600_pinout.shtml)
Obviously some people would be getting buggy PC joystick behaviour.
It clears it up for me too.
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You can get PC joystick that are digital. I'm not sure if it has problems with the software timing loop however.
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USB joysticks can be slower if there's other traffick the USB controller has to handle. Old fashioned PC joystick are being dealt with the interrupt request of the sound card, which means the CPU is interrupts it's tasks immediately to do the sound card tasks (among sound, the reading of the joystick status). That is, if we're talking DOS, not Windows as the latter has an hardware abstraction layer, and I don't know much about the implementation of that.
With the Amiga, not the CPU, but one of the custom chips (was it Paula?) is being interrupted to do the joystick handling. So, strictly spoken, it should be faster, yes.
But whether you'll notice in reality, it depends on what kind of pc you have and what kind of software you're running.
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Those monostable multivibrators were simple timer circuits which put out a pulse with width directly proportional to the joystick resistance value
Does anyone have an analogue joystick for the PC anymore?
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