jan-jaap wrote:The 4D/20 and 4D/25 have a DB9 style connector like the PowerSeries
This is plain wrong: the PowerSeries have a DB15 connector.
robespierre wrote:There are more differences than just the connector: the power supplied by the keyboard port is also different.
Personal Iris 4D/20-25 is like Power Series, it provides +12V, -12V to the keyboard, and the keyboard provides +5V,-5V to the mouse. 4D/30-35, Indigo, and Onyx provide only +8V to the keyboard. (a pin is assigned to -8V but it is not connected.) Keyboard passes +8V through to the mouse. So the mice are also different electrically.
jan-jaap wrote:all 4D-style keyboards are electrically the same
'compatible' would have been more accurate. Mea culpa
Making your own DB9 <-> miniDIN6 or DB15 <-> miniDIN6 cable is straightforward, but they also existed as genuine SGI parts. You will not fry an Indigo keyboard/mouse (the 8V model) if you use it with an older system (which supplies +/- 12V).
I usually use an Indigo keyboard / mouse set with all my older 4D systems, mostly because I don't like the optical mice. Or, actually: I can't stand the sensation of their cold, metal mouse pads against my wrist.
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