https://solhsa.com/z80/index.html
Building a game for the Spectrum from scratch in Z80 using sjasmplus
https://zxnet.co.uk/spectrum/plus3_external_floppy_cable
http://www.tzxvault.org/help.htm
http://www.fvempel.nl/3pc.html
https://digitalpreservation-blog.lib.cam.ac.uk/3-inch-treasures-transferring-material-from-amstrad-floppy-disks-52e1422a6b82?gi=a5b13b3c9cf2