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Four floppy drives with Amstrad disc interface

449 bytes added, 17:30, 22 December 2010
/* Four drives hardware modification */
The NEC765 floppy disc controller used by Amstrad can support up to 4 drives. However, in the Amstrad disc interface, only the US0 output is connected. This then decodes into two drive selects (/DRIVE SELECT 0 and /DRIVE SELECT 1).
 
The CPC6128 uses a 74LS38 (Quad 2-input NAND) to generate the select for drive 1, the select for drive 0 is generated from this using VCC, resistor and KTC1815.
With a hardware modification, internal in the CPC664, CPC6128 or 6128+, or internal to the DDI-1, the US1 output can also be connected, and now four drives can be accessed using the NEC765 directly.
Note that most Amstrad software, including AMSDOS, supports only To do this a 2 drives-to-4 decoder should be used instead.(i.e. 74LS139)
FutureOS howeverNote that most Amstrad software, can support including AMSDOS supports only 2 drives. So to use the 4 drives with a hardware modification like thisyou need to access the NEC765 directly.
FutureOS supports this hardware modification and can use the 4 floppy drives.
(As a side note, FutureOS supports 8 floppy drives, but the other 4 are provided by adding a Vortex Disc Interface in addition to an Amstrad Disc interface).
==Alternatives==
Arnoldemu
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