Sun keyboard cables: old keyboards use a DA-15 connector; new keyboards
use a miniDIN-8.  Through at least the type-5, they are all
electrically compatible, and in my experience you can use type-3,
type-4, and type-5 indiscriminately, with only passive adapters needed.

Sun sells an adapter cable for using new keyboards on old machines.
But it's expen$ive, it's unnecessary, and they don't sell one for using
old keyboards on new machines.

It's easy to wire one up.  Here's what you need to know.

Connector pinouts (male connectors viewed end-on, ie, pins pointing
towards you):

  miniDIN-8                                DA-15
   _______                  __________________________________
  /       \                /                                  \
 / 6  7  8 \               \   1   2   3   4   5   6   7   8  /
|           |               \                                /
| 3  4    5 |                \   9  10  11  12  13  14  15  /
|           |                 \____________________________/
 \  1   2  /
  \_______/

1 Gnd   5 KTx                  1 KRx   5 MRx   9 Gnd  13 (not connected)
2 Gnd   6 KRx                  2 Gnd   6 Gnd  10 Vcc  14 Vcc
3 Vcc   7 MTx                  3 KTx   7 MTx  11 Vcc  15 Vcc
4 MRx   8 Vcc                  4 Gnd   8 Gnd  12 Vcc

You thus need at least six conductors in the cable, four signal and two
power.  (Actually, you need only three signal lines, because the line
from the CPU to the mouse is not needed.  But I can never remember
whether that's MRx or MTx; I wire it up anyway.)

The cable for using a modern keyboard on an old machine thus looks like
this.  This cable plugs into the keyboard at the miniDIN-8 end and the
machine at the DA-15 end.

         +------------------------------------------------------+
         |       +--------------------------------------+       |
         |       | +----------------------------+       |       |
      +--|-------|-|--------------------+       |       |       |
+-----|--|--+    | |              +-----|---+---|---+---|---+---|---+
|     |__|__|    | |              |  ___|___|___|___|___|___|___|___|__
|    /|  |  |\   | |              | /   |   |   |   |   |   |   |   |  \
|   / 6  7  8 \  | |              | \   1   2   3   4   5   6   7   8  /
|  |      +----|-+ |              |  \                                /
+--|-3  4-+  5-|---+              |   \   9  10  11  12  13  14  15  /
|  |           |                  |    \__|___|___|___|_______|___|_/
|   \  1   2  /                   |       |   |   |   |       |   |
|    \_|___|_/                    |       |   +---+-+-+-------+---+
|      |   |                      |       |         |
|      +---+----------------------+-------+         |
+---------------------------------------------------+

The cable needed to use an old keyboard on a modern machine is the
same, except that the DA-15 is female instead and the diagram hence
shows it from the back instead of the front; this version of the cable
plugs into the machine at the miniDIN-8 end and into the keyboard cable
(which is permanently attached to the keyboard) at the DA-15 end.