[mlyle]

Breaking instructions into 3 bit groups is awfully convenient (and you find it elsewhere, e.g. in portions of the THUMB encoding).

Datapoint did it consistently. And in a way that aligns with octal encoding. And then used octal in their documentation.

In turn, their instruction set basically became the 8008's, which influenced the 8080 and then 8086/8088. In turn, we still have this structure in x86 today: the instructions are prettily readable in octal.