Pinout and notes for the MM5387 clock chip
------------------------------------------

Pinout  (40-pin DIL package)

                       +-------o-------+
                 AM  --+ 1          40 +--  PM
       10 hours b+c  --+ 2          39 +--  1 Hz
          1 hours f  --+ 3          38 +--  Select 24 Hours
          1 hours g  --+ 4          37 +--  NC
          1 hours a  --+ 5          36 +--  50 Hz Select
          1 hours b  --+ 6          35 +--  50 Hz
          1 hours d  --+ 7          34 +--  SET Fast
          1 hours c  --+ 8          33 +--  SET Slow
          1 hours e  --+ 9          32 +--  Display seconds
       10 minutes f  --+ 10         31 +--  Display alarm
       10 minutes g  --+ 11         30 +--  Display sleep
     10 minutes a+d  --+ 12         29 +--  VDD
       10 minutes b  --+ 13         28 +--  VSS
       10 minutes e  --+ 14         27 +--  Sleep out
       10 minutes c  --+ 15         26 +--  Alarm off
         1 minute f  --+ 16         25 +--  Alarm out
         1 minute g  --+ 17         24 +--  Snooze
         1 minute a  --+ 18         23 +--  OCS 
         1 minute b  --+ 19         22 +--  1 minute c
         1 minute e  --+ 20         21 +--  1 minute d
                       +---------------+

Connection notes (incomplete notes, may be of use):

pin 1      AM: Connect to anode of AM indicator LED
pins 2-22  7-segment LED segments: use common cathode LED's. 
           Segments are driven high from the 12V supply. The
           cathode voltage must be appropriate for the correct
           voltage drop across the LED segments. A voltage
           regulator can be used for this or individual
           series resistors at each segment output
pin 23     OCS: Connect to +12V
pin 24     Snooze: Connect to +12V via a push button. Pushing
           the button when the alarm sounds silences the alarm
           for a period of about 9 minutes, whereupon it sounds
           again
pin 25     Alarm out: driven high (+12V) when the alarm activates
pin 26     Alarm off: connect via a switch and pushbutton to +12V.
           When the switch is closed, the alarm is disabled.
           When the switch is open, the alarm sounds and the 
           pushbutton momentarily connects to +12V, the alarm
           is silenced
pin 27     Sleep out: driven high (+12V) when in sleep mode
pin 28     VSS: +12V power supply
pin 29     VDD: 0V ground
pin 30     Display sleep: Switch to +12V to show and set
           the sleep period on the display
pin 31     Display alarm: Switch to +12V to show and set
           the alarm time on the display 
pin 32     Display seconds: Switch to +12V to show seconds
pin 33     SET Slow: push button to +12V for slow setting
pin 34     SET Fast: push button to +12V for fast setting
pin 35     50 Hz input: This is the main clocking input for
           the MM5387. The 50 Hz signal can be obtained from
           the 50 Hz mains frequency, or by division of a 
           cyrstal oscillator. 3.2768 MHz is a convenient
           power of two, a simple counter circuit can divide
           this down to 50 Hz. 3.2768 MHz crystals are used
           in almost all digital watches and clocks, and are
           very commonly available
pin 36     50 Hz: Connect to +12V for 50 Hz operation
pin 38     Leave unconnected for 12 hour display
pin 39     1 Hz: output signal produced by dividers in the MM5387
pin 40     PM: Connect to anode of PM indicator LED