Dying PCjr drive; options?

[Tony Duell]

> Ironically, I have a 5150 with the full-length FDC with a very long port on it 
> (something like 40-pin female?) that I assume I could connect drives to... but 

It's a DC37 socket, 37 pins.

> I have no idea what the pinout is or where to obtain a cable.  I am not the 
> soldering type (watch me duck as the flying tomatoes come from the peanut gallery)

And you can actually make the cable without soldering!. The external 
cable is like the intneral drive cable in that it has the 'IBM twist' but 
with a DC37 plug on the controller end, not a card edge connector (or 
header socket for the AT floppy drive cable).

If you only want to link up one external drive, then what you need is : 

A 34 pin IDC connector to fit the signal connector on the drive. In your 
case, an IDC 34 pin card edge connector.

A length of 34 way IDC ribbon cable.

An IDC DC37 plug. 

IDC == Insulation Displacement Connector. This sort of connector can be 
crimped onto the cable without stripping or separating the individual 
wires, and without soldering.

Fit the edge connector onto one end of the cable, so that the marked edge 
of the cable corresponds with pin 1. That is, when the connector is 
plugged into the drive, the marked edge of the cable is at the pin 1 end 
of the drive edge connector. Slot the cable into the connector, make sure 
it lines up with the 'tines' and is at right angles to the connector, and 
then carefully squeeze the connector together in a bench vice.

Fit the DC37 plug on the other end of the cable. At this end, the marked 
edge of the cable shoubd be towards the pin 1 end of the connector -- 
that is the top edge when the connector is plugged into the IBM PC/Xt 
controller. And the top 3 pins are not connected -- that is the cable 
should align with the _bottom_ 34 tines in the plug. Again, make sure 
it's perpendicular, and crimp it in the vice.

That's it. 

As regards software, I'd keep the mainboard switches set to say you have 
2 drives -- the 2 intenral drives -- installed, and use DRIVER.SYS for 
the external ones. That way, your hard disk remains as C:, etc.


I do wonder how you're going to maintain classic computers if you don't 
like soldering though. I claim to be more of a hardware type, and not a 
programmer. By that I mean that I couldn't write an OS or a compiler 
or... from scratch. But I know enough about programming to be able to 
write little data conversion programs, or to understand enough machine 
code to know what the bytes on my logic analyser screen mean, or... 

In the same way, while you might not want to design a processor or even 
dive into a PDP11/45 CPU (with around 1000 ICs...), I do feel that you 
probably should learn how to make cables, enough digital electronics to 
be able to trace through simple logic circuits, and so on.

-tony