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Apple IIc Plus Secret Slot 6 SmartPort
In the course of disassembling the Apple IIc Plus firmware, I discovered a secret ProDOS block device and SmartPort implementation for the Disk II.
The implementation is complete, including read/write/format, minus a few bogus values in the SmartPort device information.
The entry points are:
| Address | Implementation |
|---|---|
| $C64E | ProDOS Block Device |
| $C651 | SmartPort |
It is possible to replace the ProDOS 8 device driver address for slot 6 ($BF1C for drive 1, $BF2C for drive 2) with the block device driver address $C64E, and ProDOS will then operate the Disk II using the firmware driver.
I wrote up the discovery here.