III.D51 — τ-Tower Machine

TTM: tuple (Q, m, b₀, Σ, δ_M, q_start, q_acc, q_rej). Finite control states, fixed m registers, fixed b₀ ports. Instruction set from 5 generators: ρ (successor), σ (tetration step), × (multiplication), ∧ (exponentiation); predicates: equality, divisibility, ∈_τ, orbit test.