The question I have is, why does the Mk1 have its buttons on the left side?

The buttons are on the left for a reason, which is that the vacuum neck of the VFD panel, used in manufacturing, is on the
bottom right. To get the buttons in the required diamond pattern, without risk of fouling the neck during assembly, which
could break the seal and therefore ruin the VFD, we had no choice but to put the buttons on the left. We couldn't put the
display on the PCB the other way up, because the 60V PSU components had to be as close to the top of the case as
possible to allow the main board to fit.

Was the knob changed to the right because of componentry or for interface?

The rotary control is on the right as a result of the buttons being on the left. That was the only place it would
fit!

We aren't going to make a reversed design display board for the American market, because this would increase
expense enormously. We'd have to mirror the PCB layout, flip the display upside down (see above for the problems
this would cause), rewrite the software to scan the display backwards and upside down (admittedly this is the
easiest part), and in general do a lot of fiddling around. Not to mention stocking two different PCBs, making them
in different quantities, needing reversed plasticwork, etc, etc.

To be honest, having tried operating the rotary control in both a left-hand-seated and right-hand-seated position, it
doesn't actually cause any problems that I can see, or anyone else who's tried it for that matter. Your arm doesn't
obscure the display, unless the empeg is mounted practically on the floor. If it's in a normal dashboard position,
i.e. approximately between the bottom and the middle of the steering wheel in height, plus or minus a few inches,
your arm tends to approach the controls from the side and below, rather than above.

I don't see its position as a major problem, honestly.

Patrick

Opinions expressed in this email may contain up to 42% water by weight, and are mine. All mine.
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Experience is what you get just after it would have helped...