Joe asked:
   >Has anyone tried making a cable to run from the PicStart Plus to a PIC
   >installed on a target board?  Unless there's something magic about
   >connection lengths, or crosstalk, or.... it seems like it could work.

Yes Joe, it can be made to work quite well if you observe various
precautions in your design, some of which are outlined in Microchip's
various articles on the topic.  In fact, from my experience the PicStart
Plus works much better than the original ProMate (the new ProMate, however
works well).

Here are some guidelines I've developed from hard experience:

1. Keep the ISP cable short: 6" to 8" max
2. Incorporate a switch or jumpers to isolate the MCLR and Vdd lines during
programing
3.  Microchip has a design for a buffer/driver interface.  I made one work,
but found it really isn't necesary if you do your target hardware design
right.
4.  Keep Rb6 and Rb7 as high impedance inputs, if you have to use them at
all in your design.  That way you won't have to use isolating jumpers on
them, and you'll be able to feed them directly from the programmer (a
lesson learned the hard way: the "data" line *must* be bi-birectional, and
there is no way to buffer it ... Microchip leaves it to you to find out).
5. With the target circuit in "program" mode (ie; jumpers pulled), keep the
capacitance across the PIC low (ie: make sure your bulk bypass cap is on
the "other side" of the isolating jumpers).  It's OK to leave your 100n cap
across the PIC.

Hope this helps,
.. Gregg

grkricor@ccs.carleton.ca