D25

 1  GND
 2  RXD 1
 3  TXD 1
 4  JUMPER    bit 0x20.7 cmos
 5  ?         bit 0x20.2 output via HC14, +5v, 12mA
 6  DSR out   bit 0x24.0
 7  GND
 8  ?
 9  #ON       == D25/11 == D15/7 == 0x20.0
10  ON        100k base 10k ground, collector to #ON
11  #ON       == D25/9  == D15/7
12  RXD 2
13  TXD 2
14  tx        bit 0x24.2
15  rx        bit 0x24.3
16  RXD 3
17  TXD 3
18  tx        bit 0x24.4
19  MBUS
20  DTR in    bit 0x24.1
21  rx        bit 0x24.5
22  V+        rs232 pump
23  +5v       7805
24  +VR       CU/?,?, before relay
25  +VB       +VR or +VRP, after relay


D15 ?

 1 D0
 2 D1
 3 D2
 4 D3
 5 DISP OFF   auf +5v legen
 6 FRAME      75 Hz positive pulses
 7 #ON        == D25/9 == D25/11 == D15/7 == 0x20.0
 8 LOAD       17880 Hz
 9 CP         looks much the same as LOAD, but really is about 8 MHz ?
10 LED "SERV" from ASIC via HC14, not 20.? nor 24.?
11 GND
12 Keyb1      from ASIC via HC14, not 20.? nor 24.?
13 Keyb2      CLK?  +5v, 10mA short, ASIC via open collector thingy
14 Keyb3      DATA? +5v,  5mA short, directly to/from ASIC
15 +12v

?
 1 DATA green
 2 NC
 3 GND  red
 4 +5v  black
 5 CLK  yellow
 6 NC

ASIC

 1 
 2 
 3 +5v
 4 GND
 5 24.0
 6 24.1
 7 24.2
 8 24.3
 9 24.4
10 24.5
11 
12 
13 INT0
14 INT1
15 INT2
...
-12 LED "SERV" inverter to D15/10
-11 ???        inverter to D15/12
...
-6 rxd1
-5 txd1
-4 rxd2
-3 txd2
-2 rxd3
-1 txd3