[julie_m]

I remember using an Amiga with a primitive voice sampler and a machine code monitor (basically a memory editor) to try to clean up a noisy recording. It was a bit laborious, having to find the right place in memory and manually enter the hex codes for the new sample values, then adjust the screen to force a redraw; and limitations of RAM (all the samples, the sampler software and the memory editor had to squeeze into the machine's memory) and lack of a hard disk drive prevented me from doing a complete side of a 78 in one go.

But at least it proved the concept in my mind: working at the individual sample level, scratches could be edited out. Nowadays, Audacity already lets you redraw the waveform manually without resorting to external hackery. But it can also do it all for you :/