1.44 MB floppys used in 880K Amiga Disk Drives

[Zac67]

Since the early 90s DD and HD floppies were made with the exact same media inside.

But: once these get written to with a HD drive (e.g. PC preformatted) they may be troublesome in DD drives. According to several experts, HD heads write 'harder' bits that are just overlayed with the 'softer' DD bits. The DD bits deteriorate faster than the harder HD ones and practically get overwritten from underneath. This effect depends largely on the exact specs of the media used (which we usually know nothing of).

I can't confirm this from my own experience though (been using an Amiga HD drive for the last 15 years), but for valuable data it's definitely worth considering. Actually I don't trust floppies further than I can throw them...

[Zac67]

HD drives can handle/overwrite 'harder' bits, so they should be fine with HD floppies whether in HD mode or not. Actually, any DD floppy ever written to in a HD drive and then rewritten in a DD drive can be a problem over time... (I don't know whether HD drives vary the write current according to the currently used density but the write field from a HD head will always be denser.)

I guess the effect largely varies with the different media types. Additionally, many late DD drives are probably using HD heads anyway, so you may or may not notice bit rot over time - but you've been warned.