Preserving a floppy disk with a logic analyzer and a serial cable

https://www.chzsoft.de/site/hardware/preserving-a-floppy-disk-with-a-logic-analyzer/

by jnord • 2 years ago

107 30 2 years ago

chzsoft.de

jgalt212• 2 years ago

The cheapest Saleae Logic Analyzer costs $499.

https://www.saleae.com/products/saleae-logic-pro-16

A Greaseweazle costs like $35.

That being said, it's always fun to hack around using the tools you have lying around. Put money already spent to good use.

vbezhenar• 2 years ago

There are much cheaper logic analyzers out there.

snvzz3• 2 years ago

I would suggest as the starting point to look at sigrok's supported hardware table[0].

I personally own a bunch of the cheap 8ch 24Msps saleae clones, which are typically below $10. I would recommend the one from muselab as it has open sourced its design.

The next step, the DSLogic, of which I have a 200Msps 16ch model.

0. https://sigrok.org/wiki/Supported_hardware

nine_k• 2 years ago

If you already have a logic analyzer, are interested in the details, and maybe are facing a tricky disk with physical damage or creative copy protection, TFA may be helpful. If you just need to read disks without hassle and expense, a Greaseweasle or another adapter us likely a more suitable choice.

rasz4• 2 years ago

How does $5 sound?

https://hackaday.com/2022/07/07/pico-makes-capable-logic-ana...

or maybe $1 with free shipping?

https://hackaday.com/2024/04/15/logic-analyzers-decoding-and...

hi-v-rocknroll• 2 years ago

Yep. I have a Greaseweazle and a Central Point Copy II PC Deluxe Option Board (and regular). Greaseweazle is largely the way to go. It's important to use the highest-fidelity method on the best FDD with the highest SNR because using a floppy disk causes wear to the media. Age also plays a factor.

I also have TEAC (2.88M, 1.44M, 1.2M, 720K, 360K, and SCSI versions), Sony, and various other FDDs.

dazhbog• 2 years ago

I remember it used to be $200 for a Saleae logic 8. Their margins on that hardware are insane..

Palomides• 2 years ago

you're really paying for the software, imo

daneel_w• 2 years ago

As a great alternative there are a handful of very cheap Saleae knock-offs using the same series of Cypress/Infineon logic chips, and they work well with e.g. Sigrok.

kees99• 2 years ago

Very cheap knock-offs have same CY7C68013 usb interface chip, but lack an FPGA that original Saleae has, so can't capture quite as fast.

Plenty fast enough for a floppy bit-stream, of course.

snvzz3• 2 years ago

Appreciate how the article documents the physical side of floppy interface and how a track is selected and read.

Then there's the (several) formats of tracks and sectors, which are left out of scope.

Mature open-source alternatives include GreaseWeazle[0] and FluxEngine[1].

They are also cheap and effective, based on off-the-shelf parts.

0. https://github.com/keirf/greaseweazle/wiki

1. https://cowlark.com/fluxengine/index.html

ThomasBb• 2 years ago

Reminds me of the applesauce project for Apple ][ disks; https://overcast.fm/+BRm0EGSWs

asdefghyk2• 2 years ago

Would not the best way to scan a deteriorating? floppy disks is with a magnetic flux measuring tool that flies very close to surface of floppy , but not touching the floppy. Recording the analogue signal, generated a require a big storage space .....

cricalix2• 2 years ago

That's what people do with tools like Kryoflux; the head of a floppy drive doesn't touch the disk, it floats above it and picks up the magnetic flux. https://www.youtube.com/watch?v=UxsRpMdmlGo covers a lot of it.

rasz4• 2 years ago

The head of a HDD floats, FDD heads slide on the surface.

pshirshov• 2 years ago

This is extremely cool, but isn't imdisk supposed to do the same?

silvestrov• 2 years ago

The graphs would be easier to read for somebody not already familiar with floppy drives if the signals (e.g. Step, Index0) were marked with direction, i.e. is it input to the FD or output from it.

beej71• 2 years ago

I would pay excellent money to get my hands on the floppies that held my childhood programs. They're long gone.

So if you're just getting started today, I recommend you keep copies of everything you do. It's fun to go back and look at, and maintaining those copies is a lot easier to do than it was in the 80s.

ck2• 2 years ago

Fun-fact the last floppy disc was made in 2011

Also the BBC seems to be running an odd number of floppy stories lately?

https://www.bbc.com/future/article/20240510-floppy-disks-why...

https://www.bbc.com/news/articles/cx82407j1v3o

Preserving a floppy disk with a logic analyzer and a serial cable

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