waltermixxx
Experienced Member
it appears to be auto repeating characters as soon as you press the key.
if I tap any key, it will generate 5 letters... if i hold it down it will just keep generating that character.
the issue is definately the keyboard... and the strobe seems to be producing 66.5 us pulses each time a character is produced...
so if i tap the A key, i will get 5 A's on the screen, and the scope shows 5 66.5 us pulses. I checked the REP key, and it's not shorted.
it isnt keyboard bounce as it does it equally with any key pressed... so it appears to be in the "strobe" section of the keyboard?
this keyboard is the classic clone keyboard with an eprom on the board and a few support chips...
Picture is here... it has a 74LS273, 2716eprom, 74LS123 on one side, and the other side of the keyboard has: 74LS42, 74LS93, NE556.
Does anyone have a schematic for this or a similar clone keyboard? or any suggestions?
Cheers.
if I tap any key, it will generate 5 letters... if i hold it down it will just keep generating that character.
the issue is definately the keyboard... and the strobe seems to be producing 66.5 us pulses each time a character is produced...
so if i tap the A key, i will get 5 A's on the screen, and the scope shows 5 66.5 us pulses. I checked the REP key, and it's not shorted.
it isnt keyboard bounce as it does it equally with any key pressed... so it appears to be in the "strobe" section of the keyboard?
this keyboard is the classic clone keyboard with an eprom on the board and a few support chips...
Picture is here... it has a 74LS273, 2716eprom, 74LS123 on one side, and the other side of the keyboard has: 74LS42, 74LS93, NE556.
Does anyone have a schematic for this or a similar clone keyboard? or any suggestions?
Cheers.
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