4000 (250-5000) Pinouts Faxback Doc. # 1445 Below are pin assignments for the Tandy 4000 : GND = Ground NC = Not Connected * = Active Low Signal Printer - DB-25 Female Floppy - 34 pin card socket ------------------------------- ---------------------------------- 1 Strobe* 14 Auto Feed* 1 GND 2 RWC* 2 Data 0 15 Fault* 3 GND 4 NC 3 Data 1 16 Initialize* 5 GND 6 NC 4 Data 2 17 Select In* 7 GND 8 Index* 5 Data 3 18 GND 9 GND 10 Motor Enable 1* 6 Data 4 19 GND 11 GND 12 Drive Select 2* 7 Data 5 20 GND 13 GND 14 Drive Select 1* 8 Data 6 21 GND 15 GND 16 Motor Enable 2* 9 Data 7 22 GND 17 GND 18 Direction* 10 Acknowledge* 23 GND 19 GND 20 Step* 11 Busy 24 GND 21 GND 22 Write Data* 12 Paper Out 25 GND 23 GND 24 Write Enable* 13 Select 25 GND 26 Track 0* 27 GND 28 Write Protect* Keyboard - 8 pin DIN 29 GND 30 Read Data* -------------------- 31 GND 32 Side Select* 1 Keyboard Clock 33 GND 34 Disk Change* 2 Keyboard Data RWC = Reduced Write Current 3 NC 4 GND Battery - 3 pin header Speaker - 4 pin header 5 +5V ---------------------- ---------------------- 6 NC 1 +Voltage 2 GND 1 Sound 2 NC 7 NC 3 NC 3 GND 4 +5V 8 NC Serial Port - DB-9 Male Power Connector (3) ----------------------- ------------------- 1 Carrier Detect 1 +12V (violet) 2 Receive Data 2 GND (black) 3 Transmit Data 3 GND (black) 4 Data Terminal Ready 4 +5V (red) 5 Signal Ground 6 Data Set Ready 7 Request to Send 8 Clear to Send 9 Ring Indicator