Make Your Own Parallel Centronics Interface Cable (most parallel printers)
The easiest way to build a Tandy 100/102 printer cable consists in finding 3 pieces:
Also, a crimper for flat cable connectors can make the job easier although it is not absolutelly neccessary.
Here's how to proceed:
Open the Centronics connector and position the flat cable so that the blue or red stripe stays on the same side as pins 1 and 19; the other end of the connector will look "empty". This is because the Tandy only uses 26 lines out of 36.
Carefully crimp the connector closed with the crimper, or gently "hammer" the back onto it using a cloth between the connector and a very solid surface (carpet doesn't do, hard wood maybe, concrete is best) and between the back and the hammer--you have to be careful, but it works.
Now, open the 26 wire connector and do the same; align the red or blue strip to pin 1 (look at the diagram below); close the connector and the cable is ready. Here's a picture of how it should look:
 
1 STROBE (Normal=High, Data read-in when Low)
2 DATA 1
3 DATA 2
4 DATA 3
5 DATA 4
6 DATA 5
7 DATA 6
8 DATA 7
9 DATA 8
10 ACKNLG (÷5us pulse,low=data rcvd and printer is ready)
11 BUSY
12 PE (high=printer out of paper)
13 SLCT (printer is in the selected state)
14 AUTO FEED XT (low=paper auto. fed one line after printing)
15 N/C
16 0V (logic ground level)
17 chassis ground
18 N/C
19-30 ground
31 INIT (normal=high, low=printer controller reset, buffer cleared)
32 ERROR (low=paper end state, off-line state, or error state)
33 ground
34 N/C
35 +5 VDC thru a 4.7Kê resistor
36 SLCT IN (low=data entry possible)
 
Tandy Parallel Printer Interface
 1 Strobe out Strobe Pulse
3,5,7,9
11,13,15,17
 PD0-PD7 out Data Bit (pdo=lsb)
19,23  NC   Not connected
21 BUSY in Busy signal to computer from prn
25 BUSY in Busy to computer from prn : high indicates device selected
 Even pins GND   Ground
26  NC   Not connected

How it looks on the back of the M102