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Checking keypad entries.
- Mechanical contacts bounce, making and breaking connections.
- For most switches a one millisecond delay is sufficient to allow oscillations to settle out.
- When a key press is detected, delay and then wait for the key to be released.
- After a release is detected, delay and then wait for the next key press.
Code from keypad. Go over checking for a switch pressed
lp: ldaa portp