Anders K Nelson

External 1.2MB 8″ floppy disk drive

Abstract:

I have a weird obsession with ancient storage media, so I bought a 8″ floppy disk drive built in 1983 and a pack of disks. I wanted the ability to read and write these ridiculous floppies but I wasn’t interested in buying a huge IBM Displaywriter to go with it.

This project is a low-level controller for the IBM 6360 with a USB interface.

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Signal	Comments
Data Bus Bit [0-7]	Typical 8-bit data bus.
Address Bit [1-4, 8]	Each disk has 77 tracks. Each track has 26 sectors of 128 bytes each. 5 address bits can locate 32 indices – perhaps these are registers in the onboard disk controller?
DMA [Request, Acknowledge, Request transmit, Request receive, Acknowledge transmit, Acknowledge receive]	Perhaps there are 3 stages: 1. A DMA write (transmit) or read (receive) is requested by the host. 2. The DMA action is acknowledged by the disk controller. 3. A data block is contiguously sent from either the host or the drive. 4. The DMA request line is deasserted.
Interrupt [1, 4, 7]	WTF
Diskette Select
Diskette Ready
I/O Read
I/O Write
Terminal Count
Select	Side select?
Reset	Obvi.

Resources:

• https://hackaday.com/2017/01/22/an-eight-inch-floppy-for-your-retrocomputer/
• http://www.smbaker.com/qume-842-8-floppy-drive-with-a-rc2014-z80-retrocomputer
• http://bitsavers.trailing-edge.com/pdf/ibm/6580_Displaywriter/
• https://www.youtube.com/watch?v=mlRQAzzwzPA
• https://www.digikey.com/short/pqrdcj
• https://github.com/roybaer/usb_floppy_adapter
• https://hackaday.com/tag/floppy/
• http://hxc2001.free.fr/floppy_drive_emulator/
• https://www.digikey.com/products/en/connectors-interconnects/d-sub-connectors/439?k=DB37&k=&pkeyword=DB37&sv=0&pv589=25&sf=1&FV=ffe001b7%2C1140050&quantity=&ColumnSort=1000011&page=1&stock=1&pageSize=25