3niti alpha has 9 directly available registers:

• -4 N: triad from memory addressed by DPn (see below);
• -3 O: triad from memory addressed by DPo (see below);
• -2 P: triad from memory addressed by DPp (see below);
• -1 F: flag register (see below);
• 0 A: accumulator register;
• +1 B: auxiliary register;
• +2 L: lower triad of current DP register (see below);
• +3 M: middle triad of current DP register (see below);
• +4 H: higher triad of current DP register (see below).

Register F is set of 3 ternary flags:

• Higher trit: RSF (Result Sign Flag);
• Middle trit: DPF (Data Pointer Flag);
• Lower trit: BCF (Borrow Carry Flag).

There are THREE 9-trit DP (data pointer) registers - DPn, DPo, DPp that are available through registers L/M/H when flag DPF has corresponding value (N, O, P respectively).

And 9-trit register PC (program counter) is not available directly (but we can copy value between PC and current DP - see Instruction Set)

Note: This architecture doesn't have register SP (stack pointer) at all!