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