U1 Voltage regulator U2 14 pin not connected U4 U3 75188 driver See 1488 Vee Vcc InA InD1 OutA InD2 InB1 OutD InB2 InC1 OutB InC2 Gnd OutC U5 75189 quad RS-232 line receiver See MC1489 InA Vcc RCA InD OutA RCD InB OutD RCB InC OutB RCC Gnd OutC RC=response control capacitor connection point U6 not inserted U7 7404 hex inverter 1A Vcc 1/Y 6A 2A 6/Y 2/Y 5A 3A 5/Y 3/Y 4A gnd 4/Y U8 7400 quad 2-input NAND* gate 1A Vcc 1B 4A 1/Y 4B 2A 4/Y 2B 3A 2/Y 3B gnd 3/Y U9 7408 quad 2-input AND* gate 27ns 1A Vcc 1B 4A 1Y 4B 2A 4Y 2B 3A 2Y 3B gnd 3Y U10 7404 hex inverter 1A Vcc 1/Y 6A 2A 6/Y 2/Y 5A 3A 5/Y 3/Y 4A gnd 4/Y U11 74157 Quad* 2-input multiplexer 27ns Pins S Vcc 1I0 /E 1I1 4I0 1Y 4I1 2I0 4Y 2I1 3I0 2Y 3I1 gnd 3Y u12 74151 8-input multiplexer (Philips) In3 Vcc In2 In4 In1 In5 In0 In6 Out In7 Outinv Sel0 Enable Sel1 Gnd Sel2 u13 74373 Octal D type latch /OE Vcc Q0 Q7 D0 D7 D1 D6 Q1 Q6 Q2 Q5 D2 D5 D3 D4 Q3 Q4 gnd LE U14 Motorola Mc68705U3S 8 bit micro controller with ROM + RAM 40 pin u15 am7910pc Slow speed FSK modem (AMD*) U16 LM386N-1 Low power Audio Amplifier Gain Gain In- Bypass In+ Vsupply Gnd Out U17 7189 iic 14 pin U18 mc1400 1b 14 pin quad nore gate Vcc U19 mc14040 12 stage binary ripple counter Q12 Vcc Q6 Q11 Q5 Q10 Q7 Q8 Q4 Q9 Q3 reset Q2 clock GND Q1 U20 7408 quad 2-input AND* gate 27ns 1A Vcc 1B 4A 1Y 4B 2A 4Y 2B 3A 2Y 3B gnd 3Y U21 X2444 16*16 serial NOVRAM http://www.xicor.com/xicor/datsheet/x24c44.htm http://www.xicor.com/xicor/graphics/x24c44.gif pins CE chip enable Vcc SK serial clock Store (inverted) DI serial data in Recall =recall DO serial data out Vss ground Interface to 6805 MPU U22 14 pin not inserted U23 MC1458 dual 741 OpAmp Out1 V+ IN1- OUT2 IN1+ IN2- V- IN2+ U24 none U25 4N38A isolator 6 pin In+ base In- C(NPN) nc Em