[tzs]

An interesting thing about the KA-10 is that those DTL registers were optional. Architecturally the registers are simply the first 16 words of core memory. If you bought the fast register option with your KA-10 they installed the DTL registers which overlaid the first 16 words of core.

A consequence of that was that anything that took a memory address could access the registers as memory. Just give it an address in [0,15].

That included the program counter. Load code in 0-15 and jump to it and it would run quite a bit faster than if it were in core if your KA-10 had the fast register option.