The Apple Disk ][ interface timing information #Apple #Floppy

The Embedded Microcontroller blog believed the information available online on the Apple ][ disk interface appears to be somewhat incomplete. To fix this, there is now a blog post for the additional information.

I have captured these waveforms from a vintage Apple IIc computer. The IIc has a disk expansion port on the back where you can get easy access to the control signals. Since all of the control signals go to both the internal drive and the expansion external drive, it provides an easy method to snoop on real signals while using the internal drive. Schematics of the Disk II interface circuitry for the Apple II+ here.

The blog has several beautiful timing diagrams to explain how the signals go in different operations.

Check out the post here.


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