AH = 01h: Report If Character Available

This function examines the keyboard input buffer to see if a scancode/ASCII pair is available. If a pair is available, it is returned without removing it from the buffer. The function returns after the first interrupt (generally a Timer Interrupt), regardless of whether a scancode/ASCII pair is available. Note that this function discards certain keycodes. See "I16Clip" on page 3-113 for more information. Use function 11h for the extended scancodes.

• Input: AH = 01h
• Output: Zero flag is clear if character is available:
  AH = Scancode
  AL = ASCII character code, or
  00h for a special scancode
  Zero flag is set if no characters are available:
  AX is indeterminate

• Error conditions: None
• Registers modified: AX, Status