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USB2FDC project

NobodyIsHere

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Dec 21, 2006
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The purpose of this thread is to discuss a USB to Floppy Disk Controller (USB2FDC) project. The goal of the project is to build a completely open source USB to Floppy Disk interface which is able to read/write soft sector FM and/or MFM formats of 3.5", 5.25", and 8" floppy disks.

The project is open to the vintage computer/retrobrew computer community to develop the USB2FDC PCB and software in a similar fashion to the original XT-IDE project. The XT-IDE was a community project of "many hands" each contributing various aspects such as hardware development, building and testing prototype boards, software development, IBM PC ROM BIOS development, documentation, etc. There is no timeline for completion as that will depend on community involvement and individual participation. It'll be done when its done and there is no estimate for completion.

The baseline hardware design is based on an 8MHz Z80 CPU, 32KB SRAM, 32KB EEPROM, a 16550 UART with 5V TTL serial to USB interface and legacy serial interface, and a WD2793 Floppy Disk Controller. The plan for software is to reuse and modify various pieces of the SCSI2IDE project and the S-100 ZFDC projects.

The USB2FDC project should at a minimum be able to read and write common soft sector FM and/or MFM floppy disks such as the various IBM PC formats and some common CP/M formats. The goal is to provide a serial menu interface to the device via the USB serial cable.

Along with what this project is intended to do it is important to state what the project will NOT support:
1. direct hardware compatibility with IBM PC floppy controller (i.e. not based on IBM PC or AT NEC765 FDC chip)
2. hard sector floppy disks
3. Group Code Recording (GCR) based floppy formats (Apple II, C=64, early Mac, some Amiga, etc.)
4. Exotic or unusual modulation schemes such as MMFM or RX02
5. Copy protected floppy disks
 

NobodyIsHere

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I am leaving out the project phase of the ultimate USB2FDC interface to the operator because that can vary widely depending on implementation and individual preference. There is no "one size fits all" due to the subjective nature of individual uses. Personally, I envision a dedicated floppy disk "file manager" type application which allows file exchange to and from the floppy disk using the USB serial interface. Such an application or applications could be developed for various operating systems and take many forms so I feel it is best left for the community to address specific implementations. These could also include block device drivers/kernel modules depending on individual participation.
 

NobodyIsHere

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Dec 21, 2006
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The current USB2FDC schematic, PCB layout, and 3d rendering of the PCB is stored on this thread on retrobrewcomputers.org

Since the project is open source, all of the hardware EDA files are in KiCAD and will be posted publicly once they are ready for prototype PCBs. In the meantime as the design evolves check with the above thread to see the latest hardware information.
 
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