How to hurt your ikbd in software

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MasterOfGizmo
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How to hurt your ikbd in software

Postby MasterOfGizmo » Thu Jul 18, 2019 6:54 pm

Usually computers are designed in a way that you cannot program them to exceed their technical limits. But while looking that the keyboard schematics

Image

it becomes obvious that there is something that might hurt the ikbd a little bit:

- switch the Port 4 to input mode
- enable the 74LS244 by driving P20 low
- Read the state of the LS244 outputs by reading Port 4
- Switch port 4 to output
- Write the opposite of the state read before to Port 4

This way all eight data lines of the 74LS244 will drive against the output port 4. This will probably not do any instant harm. But doing that for a few minutes might lead to the LS244 and/or the HD6301 to get a little warm and in the long term it could even cause damage.

And since one can upload custom code the IKBD it's actually possible to do that ....
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Orion_
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Re: How to hurt your ikbd in software

Postby Orion_ » Thu Jul 18, 2019 7:20 pm

now we need to make a boot disc virus with that knowledge :)
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Greenious
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Re: How to hurt your ikbd in software

Postby Greenious » Thu Jul 18, 2019 7:24 pm

Same is true for the RTS pins of the ACIAs. They are connected...
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