“Purpose
If there’s one criticism I hear more often than any other about the pi, it’s “I wish my Raspberry Pi had a floppy drive“. It’s really shocking that the pi doesn’t have the ubiquitous 34-pin floppy header that we all know and love. How else are you supposed to interface your Tandon TM100-2A or your Teac FD-55BR or even, for you cutting edge folks, your Sony MFP290 3.5” high density drive?
So I set along to create this much needed had, the missing link between the raspberry pi and the floppy disk drive.
Design
I’ve used the WD37C65 floppy controller IC a few times in the past, most notably as part of a floppy interface project for the RC2014 computer. I’ve previously played with the RomWBW CP/M distribution for the RC2014, and the floppy drive that’s contained as part of it. So I knew this chip reasonably well and decided to go ahead and make use of it for my raspberry pi project.
The WD37C65 is a great single-chip solution, combining the floppy controller, data separator, and control latch. It actually has three different chip selects, one for the controller, one for the DOR (disk operation register?) and one for the DCR (disk configuration register?). You can easily interface it with a plethora of vintage drives, everything from your basic 360KB floppy drive to your 1.44 MB high density drive. Yes, I’m pretty sure when working on the RC2014 I interface it to some old 8″ qume drives as well. There are several selectable data rates, and you can program the number of tracks, number of heads, number of sectors, and bytes per sector. The controller can be used with an interrupt or it can use polling. It’s a great vintage IC to use.”