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B-33. Function Name: STOP

Purpose: Check if <STOP> key is pressed
Call address: $FFE1 (hex) 65505 (decimal)
Communication registers: A
Preparatory routines: None
Error returns: None
Stack requirements: None
Registers affected: A, X

Description: If the <STOP> key on the keyboard was pressed during a UDTIM call, this call returns the Z flag set. In addition, the channels will be reset to default values. All other flags remain unchanged. If the <STOP> key is not pressed then the accumulator will contain a byte representing the lost row of the keyboard scan. The user can also check for certain other keys this way.

How to Use:

  1. UDTIM should be called before this routine.
  2. Call this routine.
  3. Test for the zero flag.


   BNE *+5     ;KEY NOT DOWN
   JMP READY   ;=... STOP

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This page has been created by Sami Rautiainen.
Read the small print. Last updated December 17, 2002.