KBPATN = 0x4F;                   // Define pattern.
KBMASK = 0x4F;                   // Define P0 pins that trigger int.
KBCON  = 0x00;                   // Pattern must not match.
EKBI   = 1;                      // Enable keypad interrupt.
PCON  |= 0x03;                   // Total power down.

// ZZzzz....                     // ZZzzz....
// ZZzzz....                     // ZZzzz....

PCON  &= 0xFC;                   // Power back up.
KBMASK = 0x00;