Agat floppies are either 140K GCR (format is identical to Apple's) and 840K MFM (80 tracks, 2 heads, 21 sectors, 256 bytes per sector), but the address marks etc. aren't standard: https://raw.githubusercontent.com/sintech/AGAT/master/docs/agat-840k-format.txt

Hooked this up to SAMdisk via quick copy/paste and it does seem to work smile

Code
80 Cyls 2 Heads:
250Kbps MFM, 21 sectors,  256 bytes/sector:
  0.0  14 15 16 17 18 19 20 0 1 2 3 4 5 6 7 8 9 10 11 12 13 
  1.0  11 12 13 14 15 16 17 18 19 20 0 1 2 3 4 5 6 7 8 9 10 
  2.0  7 8 9 10 11 12 13 14 15 16 17 18 19 20 0 1 2 3 4 5 6 
  3.0  19 20 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 
Warning: unknown MFM address mark (6B90) at offset 2 on cyl 4 head 0
  4.0  11 12 13 14 15 16 17 18 19 20 0 1 2 3 4 5 6 7 8 9 10 
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