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== 8-bit usage ==
ADFS on 8-bit systems required a WD1770 or later 1772-series floppy controller, owing to the inability of the original Intel 8271 chip to cope with the double-density format ADFS required. ADFS could however be used to support a hard disc without a 1770 controller present. The 1770 floppy controller was directly incorporated into the design of the Master Series and B+ models{{Fact|date=June 2007}}, and was available as an 'upgrade' board for the earlier Model B. The Acorn Electron's floppy interface (Acorn Plus 3) was an add-on unit, initially available through Acorn and later Pres (aka Advanced Computer Products). The ACP implementation of ADFS fixed a flaw in the Acorn version, that required the use of a file named ZYSYSHELP. On the Electron, Disk corruption could also occur if attempting to use the <tt>*COMPACT</tt> command without disabling the blinking cursor. This was due to the fact that the <tt>*COMPACT</tt> command used screen memory as working space during the operation, and the blinking cursor corrupted that memory space<ref>http://www.portices.fr/formation/Res/Info/Dimet/Ordinateurs/AcornBBC/www.stairwaytohell.com/Ressources/r-EU-ACP-E00ADFS.html</ref>.
ADFS supported hard discs, and 3½" [[floppy disc]]s formatted up to 640 KB capacity using double density [[Modified Frequency Modulation|MFM]] encoding (''L'' format; single-sided disks were supported with the ''S'' format (160 KB) and ''M'' format (320 KB)). ADFS as implemented in the BBC microcomputer system (and later RISC OS) never had support for single-density floppies.
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