Amiga external floppy communications protocol

[Jim]

Hello,
I'm trying to interface with an Amiga 500 through the external floppy
drive port. I've tried to present my device to the Amiga like a drive
with no disk in it but Workbench puts up an Icon on the Desktop
"DF1:BAD".

I've tried snooping an external drive to see what it does but I
haven't been able to figure it out. Can someone help me with how a
floppy drive communicates to an Amiga when there is no disk inserted?

Thanks,
Jim

[Michael van Elst]

Post by Jim
Hello,
I'm trying to interface with an Amiga 500 through the external floppy
drive port. I've tried to present my device to the Amiga like a drive
with no disk in it but Workbench puts up an Icon on the Desktop
"DF1:BAD".
I've tried snooping an external drive to see what it does but I
haven't been able to figure it out. Can someone help me with how a
floppy drive communicates to an Amiga when there is no disk inserted?

An external floppy needs two magic things.

An identification circuit, so that it is recognized.
A diskchange signal that is cleared by the step pulse.

Here is a nice adapter circuit that can be used:
http://www.ianstedman.co.uk/Amiga/designs/Floppy_Adaptor/floppy_adaptor.html

N.B. High density drives may or may not have problems reading or writing double
density media. And of course, you cannot use high density media with an Amiga.

[Thomas Richter]

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[Ralph Spitzner]

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