A few days ago, I had a blast from the past !

While looking for a multi-position switches in the local store, the clerk proposed a type of switch I had totally forgotten !

The impressive interlocked switch !

I initially wanted to use rotary buttons but you can't find all the options and it takes some turning...

These buttons solve most of the problems I had, they use more room but they provide a direct access to everything. With about 50 buttons (and 2 rotary Hex encoders) one can select a whole instruction with a few pushes. Some rows or selectors can be enabled or inhibited, the conditions and the IMM knobs can be selected depending on the format selectors...

Here is the first sketch :

I just ordered more parts to start prototyping...

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These switches are quite awesome. There are rotary switches but turning them all the time would quickly become ... hmmm...

I keep the rotary selectors for the numbers but the opcode, the condition and register names now have their own button. These are not inherently linear things but symbols. So it's good to point directly at them and push the right button right away, instead of blindly turning a selector until it reaches the desired position.

The other advantage is more technical : these switches can come in 2PDT, 4PDT, 6PDT and even 8PDT ! This means that a lot of signals can be encoded directly at the mechanical level, reducing the amount of diodes and relays ! For the main parts I have chosen 4PDT and the IMM4/IMM8/REG selector is 8PDT.