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fluxengine/doc/disk-acornadfs.md
2025-08-20 21:23:02 +02:00

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acornadfs
====
## BBC Micro, Archimedes
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Acorn ADFS disks are used by the 6502-based BBC Micro and ARM-based Archimedes
series of computers. They are yet another variation on MFM encoded IBM scheme
disks, although with different sector sizes and with the 0-based sector
identifiers rather than 1-based sector identifiers. The index hole is ignored
and sectors are written whereever, requiring FluxEngine to do two revolutions
to read a disk.
There are various different kinds, which should all work out of the box.
Be aware that Acorn logical block numbering goes all the way up side 0 and
then all the way up side 1. However, FluxEngine uses traditional disk images
with alternating sides, with the blocks from track 0 side 0 then track 0 side
1 then track 1 side 0 etc. Most Acorn emulators will use both formats, but
they might require nudging as the side order can't be reliably autodetected.
## Options
- Format variants:
- `160`: 160kB 3.5" or 5.25" 40-track SSDD; S format
- `320`: 320kB 3.5" or 5.25" 80-track SSDD; M format
- `640`: 640kB 3.5" or 5.25" 80-track DSDD; L format
- `800`: 800kB 3.5" 80-track DSDD; D and E formats
- `1600`: 1600kB 3.5" 80-track DSHD; F formats
## Examples
To read:
- `fluxengine read -c acornadfs --160 -s drive:0 -o acornadfs.img`
- `fluxengine read -c acornadfs --320 -s drive:0 -o acornadfs.img`
- `fluxengine read -c acornadfs --640 -s drive:0 -o acornadfs.img`
- `fluxengine read -c acornadfs --800 -s drive:0 -o acornadfs.img`
- `fluxengine read -c acornadfs --1600 -s drive:0 -o acornadfs.img`