^10 - The Keyboard (Button) Port

This port is a read only value of the last button action on a user interface.
It only reports the last change as either a press or release.
The value is a bitfield with the MSB (bit 8) as the state and the first 7 bits as the button number.
MSB cleared indicates the button is pressed. MSB set indicates the button is released. Therefore button 1 release is 0x81, button 11 release is 0x8b etc.

This only reports the last button action. Unlike the DIP Switch Port it does not report the current state of all buttons.

Syntax

LDA ^10,x
Where x is the bank of up to 16 buttons you want the status of.
LDA ^10,0 will give the last transition of buttons 1-16.
LDA ^10,1 will give the last transition of buttons 17-32.

^10 Keyboard port responses
Button Number	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16
Press Value	0x01	0x02	0x03	0x04	0x05	0x06	0x07	0x08	0x09	0x0a	0x0b	0x0c	0x0d	0x0e	0x0f	0x10
Release Value	0x81	0x82	0x83	0x84	0x85	0x86	0x87	0x88	0x89	0x8a	0x8b	0x8c	0x8d	0x8e	0x8f	0x90

This port will not record a two button press. It will only report the latest button action. You would need to rapidly check the port twice and have your task recognize that there were two back to back press events without a release event.

Examples

Example showing one task managing multiple buttons.

Task1()
{
// One Task can handle many buttons:
LDA ^10,0      // Get the keyboard port
CMP #0x01      // Was it a button 1 push?
BRZ B1PRESS    // Yes, go do button 1 press stuff
CMP #0x81      // Was it a button 1 release?
BRZ B1RELEASE  // Yes, go do button 1 release stuff
CMP #0x02      // Was it a button 2 push?
BRZ B2PRESS    // Yes, go do button 2 press stuff
NULL           // Not a combination we are interested in, so end Task
...
}