TT: Intermittent phantom key & mouse button presses.

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stephen_usher
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TT: Intermittent phantom key & mouse button presses.

Post by stephen_usher » Sun Jun 28, 2020 10:54 pm

OK, here's another strange one.

Every now and again my TT decides that either the right mouse button is constantly pressed or Ctrl-Space is being typed repeatedly but intermittently. This happens with any mouse in the port, so it's not the mouse. The 5V line is something like 5.08V and as smooth as silk according to the oscilloscope.

When this happens a warm reset (Ctrl-Alt-Del) or the reset button doesn't fix it but a cold boot (Ctrl-Alt-Shift-Del) does. Unplugging and replugging in the keyboard makes no difference.

All I can think of is that the pull-up resistor on the keyboard RX line is going faulty and the line is floating, causing the system to think that the keyboard is in some strange state, or there's some other hardware problem lurking somewhere. A gremlin that's being fed after midnight.

Any ideas?
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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Re: TT: Intermittent phantom key & mouse button presses.

Post by exxos » Sun Jun 28, 2020 11:02 pm

Wasn't this some OS bug which was never solved ?
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Re: TT: Intermittent phantom key & mouse button presses.

Post by mikro » Mon Jun 29, 2020 8:01 am

AFAIK, that is the ESC bug.

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Re: TT: Intermittent phantom key & mouse button presses.

Post by stephen_usher » Mon Jun 29, 2020 10:45 am

Oh, I've not heard of that one. What is it precisely?

The reason I asked is that I've been seeing the problem more and more recently. I've switched over to using an Eiffel temporarily as the TT keyboard was becoming almost unusable some days.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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arkadiusz.makarenko
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Re: TT: Intermittent phantom key & mouse button presses.

Post by arkadiusz.makarenko » Mon Jun 29, 2020 10:53 am

Was it a bug in MPU firmware or OS?
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Re: TT: Intermittent phantom key & mouse button presses.

Post by stephen_usher » Mon Jun 29, 2020 4:59 pm

After resoldering the DB9 ports and all the other connectors on the keyboard board and cleaning the DB9 contacts with very fine sandpaper the keyboard seems OK again. I wonder if it was poor contacts making spurious signals.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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