The arbitrary length numbers in the 1401 are interesting because they really are arbitrary length. For instance you can work with 1000 digit numbers if you want

The arbitrary length numbers in the 1401 are interesting because they really are arbitrary length. For instance you can work with 1000 digit numbers if you want. I made two 1000-digit numbers and multiplied them with a single instruction. The console lights on the 1401 flashed like crazy while the hardware multiplier chugged away. A full minute later it had the answer. Yes, a single instruction took a minute to run.