TRS80 Model 3 i/o connectors - test-drb@ccmp.vtda.org

31 Oct 2002

...
  From: Tony Duell &lt;ard(a)p850ug1.demon.co.uk&gt;

...
  Most of the I/O connectors are on the bottom...

Okay, *bottom of the unit towards the rear* :>)

...
  So far, so good. I assume you've identified the
mains input as well. 
Yeah, that would be pretty hard to miss!

...
  On the bottom are 4 connectors. The 2 neares the back
of the machine are 
 on the CPU board and consist of the parallel printer port (34 pin, 
 towards the floppy drive side of the machine) and the I/O expansion bus 
 (50 pin). 

 In front of the parallel port is another 34 pin edge connector, which is 
 part of the floppy controller card. It's for external floppy drives (You 
 can connect 2 more drives here, I think you set them as DS0 and DS1, and 
 you need to terminate the last drive on the cable).

 In front of the I/O bus is the DB25 RS232 port.

 > parallel port as a 34-pin card-edge connector (which I suppose needs a
 > Tandy-specific cable to attach to a printer), but the problem is that there
...

 Yes, but it's an easy cable to make up. It's just a 34 pin edge connector 
...
  on one end of a piece of ribbon cable and a 36 pin
Blue Ribbon 
 ('Centronics') plug on the other. Leave pins 18 and 36 on the BLue Ribbon 
...
  connector unconnected, match up the pin 1s of the 2
connectors. Then just 
...
  crimp the connectors onto the cable -- there are no
twists or swaps to 
 worry about. 
Thanks for the information.  I'll be poking around this critter more this
weekend.  Any gotchas I should know about?

Later --

Glen
0/0