weedeewee wrote on 2023-06-13, 14:52:There is only one 556, which serves two axis.
That multi io card does not support four axis, and very likely not even four joys […]
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Jo22 wrote on 2023-06-13, 14:34:a) please don't scream, it's unpolite.
b) the diagnosis program said the axis test failed.
So it's not wrong investigating this […]
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maxtherabbit wrote on 2023-06-13, 14:11:
the timer ICs and their associated circuitry have NOTHING to do with the button inputs, only the axis
a) please don't scream, it's unpolite.
b) the diagnosis program said the axis test failed.
So it's not wrong investigating this further.
Maybe the axis can be made work and the gameport can be saved.
c) I know what a timer IC is. I worked with 555s for about 20 years.
From what I learned tinkering with electronics is to never make assumptions.
The most weird things can be the culprit.
Going by logic makes sense, but isn't the last word in wisdom.
There is only one 556, which serves two axis.
That multi io card does not support four axis, and very likely not even four joystick buttons.
I already mentioned this before you started talking about the 556.
Yes, I understand and fully agree. Under normal circumstances I wouldn't say a thing, also.
An usual gameport card has a 558 and support for two joysticks, with two buttons and x/y axes each.
Not sure if that diagnostic program knows about the existence of one-joystick game cards, either.
It didn't explicitly say that axes of joystick 1 or 2 is faulty, it's pretty vage, rather. 🤷♂️
It's just that the 556 is a timer IC/oscillator. It's an unpredictable source of error, thus.
If it oscillates wild due to a defect, it may introduce RF noise into nearby 74 series ICs or those directly connected to it.
And in thus case, the gameport cable was attached in reverse, so I thought maybe there was a short when the
joystick was used while the diagnostic program was running and told to press all buttons.
I didn't check the pinout when I wrote this, though.
That's why I was worried, mainly. I'm not insisting that the 556 is the troublemaker.
I just meant to say that everything could be a source of error.
In practice, it's often the thing that someone expects the least.
There's an old saying that jokingly says "everything oscillates, except the oscillator."
Edit: If the card was on my workbench, I'd use an oscillograph (scope) and check the ICs.
However, the user doesn't have that equipment at home, so it's no option.
Edit: Or let's thinking the other way round.
How could something simple as the gameport be possibly broken?
It contains address decoders, a multi-555 IC (that 556) and caps to define a time base.
On the joystick side, we have variable resistors (two potentiometers) that control the charging/discharging curve of the caps, so X/Y axes can be measured. The rest are switches.
Edit: If we just want to make the gameport silent, cutting the right pin of one the adress decoder ICs is an option.
Alternatively, let's just remove that card and use a Sound Blaster with on-board IDE/ATAPI.
A 286 can also boot from a Secondary Master IDE port if XTIDE Universal BIOS is used (on an EPROM on a network card).
If configured accordingly, it will boot from both Primary/Secondary Master.
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