Steve at Big Mess o’ Wires has resumed work on his Macintosh floppy drive emulator project. Previously he had developed the project on a breadboard using an Altera EPM7128S CPLD and an Atmel ATMEGA32u4 microcontroller. Now he has assembled it on a project board and updated some of his components. He writes:
The firmware has now been partially converted to the new microcontroller and pin arrangement, and I’m able to read the SD card and write to the LCD screen without problems.
For those who may have missed the earlier progress updates, Floppy Emu is a floppy disk drive emulator for classic Macintosh computers like the Mac Plus. It plugs into the Mac’s DB-19 port, and behaves exactly like an external Sony 3.5″ disk drive would, so no special system software or other modifications are required. Floppy disk images are stored on a standard SD memory card, and a microcontroller (Atmel ATEMGA1284P) and CPLD (Xilinx XC9572XL) are used to read/write the floppy data. The data is converted into the GCR-encoded serial pulse stream that the Mac expects, exactly like the signal from a magnetic read head flying across a track on a real floppy disk.
You can get more photos and project info at Big Mess o’ Wires.