The 8080 lacked this, but even though the 8086 was more or less based on the 8080, this probably inspired the 8086 LOOPNZ instruction. Same idea, hardcoded to use the CX register instead of B on the Z80. The unoffical nicknames for the AX, BX, CX, DX were accumulator, base, count, and data. CX was used for the count for all looping and string move instructions. Similarly, BX was special purpose for indirect operations and AX/DX for certain logic and arithmetic instructions.