SPACEWAR! Switch Boxes for a PDP-12

Brent Hilpert bhilpert at
Sun Sep 23 15:47:53 CDT 2018

On 2018-Sep-23, at 7:46 AM, Michael Thompson via cctech wrote:
> Visitors to the RICM like to play SPACEWAR! in the PDP-12. Unfortunately
> using the console switches is uncomfortable, not intuitive, and is tough on
> the switches. We would like to recreate the switch boxes used on the PDP-1
> to make playing a better experience.
> We modified the source
> <>
> from D.E. WREGE
> <;fn=images/jby/jbyos8.tu56;to=ascii;blk=510,131,0;plain=1>
> to use the LINC SXL instruction to read the PDP-12 GPIO signals, and
> prototyped two switch boxes using recycled toggle switches. This works
> great, so now we need to make better switch boxes.
> This CHM article shows what we want to recreate.
> <>
> This article shows a sketch of the switch boxes.
> <>
> A generous donor made these boxes for us.
> <>
> The lever switches are turning our to be difficult to find at a reasonable
> price. We found some NOS SwitchCraft lever switches that looked like the
> sketch and the PDP-1 pictures and were a reasonable price, but our order
> was rejected because they only had one in stock. eBay has Mossman and
> SwitchCraft, but they are either very expensive (more than $50 each), or
> they only have one available.
> The switches that we are looking for need to be SPDT, three-position,
> non-locking, center off. (If the switches have more than one pole we can
> remove the extra poles to keep the operational force low.) Before we cave
> in and buy some modern C&K toggle switches, does anyone have a source for
> Mossman or SwitchCraft switches at a reasonable price?

I have some options that might be suitable but you haven't provided much detail about what's ideal or limits you're willing to entertain in style of switch.
Are you trying to be period-correct?

 . . there are a wide variety of lever switches available.
There are leaf-contact switches that mount with two screws and a slot for the lever,
leaf-contact with a throated actuator that mount in a 1/2 inch hole (much easier to mount than making a narrow slot),
wafer switches with the two-screw/slot mount, etc.
Slot-styles may have the lever plane made from stamped/sheet metal with a slide on knob vs. made from thick ~3/16-1/8 inch metal with a thread-on knob.
The latter were very robust and the type typically found in telephone switchboards, although there were also some cheaper japanese makes.

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