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486 Board - Keyboard & PC speaker problem?

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First post, by Silent Loon

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I noticed a strange behaviour with one of my 486 boards (after I repaired the PC speaker - resoldered the cables). Its a UMC based 486 PCI board. The pc speaker beeps very often when I press a keyboard button to long or accidentically press two keys at the same time. I doesn't happen allways but frequently.
System uses AMD 486DX4-100 and 24MB Ram.
Phoenix Bios

Testing various bios settings didn't change anything. Happens in bios, in freedos & MS-Dos, so it doesn't seem to be driver or OS related.

Any suggestions what the reason for this could be?
Apart of the frequent "beeps" the system seems to work flawlessly.

Reply 1 of 5, by Silent Loon

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Okay, I plugged in my old Siemens AT keyboard - no hysterical beeps anymore.
Seems to be some kind of incompatibility of the PS2 keyboard /adapter.

Nevertheless this was the first time that such a problem appeared.

Reply 2 of 5, by h-a-l-9000

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There's nothing intelligent in the mini-DIN adapter so it's likely an incompatibility in the keyboard controller firmware or a bug in the Phoenix BIOS.

1+1=10

Reply 4 of 5, by h-a-l-9000

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Well it does work with all your other 486s? But yes it's possible that the others are more tolerant to nonstandard/'stretched' keyboard protocols.

1+1=10

Reply 5 of 5, by Silent Loon

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I plugged in an old Cherry PS2 keyboard. No problems so far. So it seems to be an issue of the prodikeys (perhaps because you can use it as a midi input device as well?).

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