What began as one developer’s need to test a Floppy Emu device grew into a full set of SWIM driver fixes for aging Apple hardware.
Here’s a blast from the past, and I’m guessing good news if you’re running a 35-plus-year-old Mac. That would be going back all the way to Linux’s early days, and maybe before.
Oh, and remember floppy drives, the working person’s way of moving data on and off personal computers? They’re in this story too.
On Thursday patches dropped for the Linux driver for the floppy disk controller in Apple’s legacy SWIM — often expanded as either “Super Wozniak Integrated Machine” or “Super Woz Integrated Machine” — affecting hardware going back to 1988. There were a large number of patches, for improving performance and fixing some very old bugs.
It seems that Finn Thain, a Linux m68k dev — meaning he contributes specifically for Motorola 68000 series of processors, which Apple used way back when — started out by scratching a small itch. That ended up leading him down a rabbit hole, according to a notification that showed up on the kernel mailing list:
I recently had a need for the ‘swim’ driver but found that it was too buggy to be useful for my purposes. I had two aims in mind–
Firstly, I needed this driver to help me test my new BMoW Floppy Emu for emulation correctness. Being that Linux is open source and MacOS is not,
this driver should be ideal for that.Secondly, I needed to realign the heads in some disk drives. The swim driver has most of the code needed for a feedback loop for manual re-alignment, so I wrote the remaining code and pushed it to a repo here: https://github.com/fthain/linux/commits/swim/
These patches fix all the bugs I found. They improve stability, compatibility and performance. Additional patches improve source code quality by removing redundant code and cleaning up a bit.
This patch series was successfully tested on the following systems.
Mac Quadra 650 – SWIM 2 with Mitsubishi FDD
Mac LC III – SWIM 2 with Mitsubishi FDD and Sony FDD
Mac Quadra 700 – SWIM with Sony FDD
Mac IIvx – SWIM with Sony FDD
While some of these testing machines don’t go all the way back to the 1980s, they are at least from the early 1990s. That’s pretty early on the Linux timeline. In an age when we no longer support 32-bit machines, I’m impressed that we’re doing something to keep these historical artifacts alive.
Christine Hall has been a journalist since 1971. In 2001, she began writing a weekly consumer computer column and started covering Linux and FOSS in 2002 after making the switch to GNU/Linux. Follow her on Twitter: @BrideOfLinux
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