Let's break orthogonality again !

Imm3 is pretty lousy and can make only very short loops, 4 instructions maximum. Where and how can I get more bits ?

The condition code is a good candidate: there is one "negate" flag, and 3 source bits. 4 sources are external arbitrary, configurable signals, but are they required ?

Let's drop those extra conditions in the "short immediate" format so Imm3 becomes Imm4. The extra conditions are still available with the register form, because there are only 8 source registers. And I don't want to get rid of the extra conditions because they will be very handy later, when used as a microcontroller: that thing is meant to deal with I/Os and it's a nice feature to inherit from the CDP1802 ("The 1802 has a single bit, programmable and testable output port (Q), and four input pins which are directly tested by branch instructions (EF1-EF4).").

The diagrams must be updated or redrawn and the assembler must be modified...