Dan Maloney
Let's get started everyone. Welcome to the Hack Chat, please pardon my typing -- sprained my finger yesterday. I'm Dan, I'll be modding today along with Dusan as we welcome Adafruit for their first Hack Chat of 2022!
We've got a livestream setup on YT - there it is ^^^
💾💾💾
So the setup is to ask questions here, and they'll answer over on the live stream, plus they'll text answers here too
A multimedia extravaganza!
wow!
hi its ladyada! if you can't get parts, why not get ones that are no longer even made anymore! so ... retro tech :)
floppy disks! both simpler and more complicated than you may think
Can you even find floppies in e-waste anymore?
a LOT of floppy disks were manufactured
there is nothing electric about floppiesw
Hi! I'm Jeff, and I work with Adafruit mostly on CircuitPython. Limor pulled me into this floppy project, and I'm having a blast getting back into the retro computing aspect of it.
More likely than getting new microcontrollers @Dan Maloney
and computers pretty quickly removed floppy drives, i think the market was a little 'shocked'
Sorry -- floppy drives
yes often folks who toss our computers have delicious floppy drives in there
rescue them :)
PT gets the best stuff like signed "hackers" floppies
But getting more rare. I am currently on the search for (a lot of) drives and it is getting harder to get them.
goodwill, flea markets, and ebay are pretty good
Some time ago you could get them anywhere computers were replaces. Schools mainly. But now known good drives can get quite expensive
try to get an usb floppy drive
Extracted a drive from an old system the other day, but it's getting increasingly difficult to know that they're in alignment. I remember there was a Hackaday article discussing a Yamaha Disklavier with its floppy out of alignment.
a looooooooot of disk drives were made. they are out there
I'm doing stuff with vintage media that's a little more esoteric. Hard sectored 5.25" and 8" drives are my focus right now. Looking to image disks and emulate the drives.
why don't usb floppy drives always work? limor is answering ...
Limor's showing on the stream what's in a USB floppy
for example, the prince floppy can't be read with a USB floppy drive (mac)
drive
There's a laptop floppy drive + a USB controller (no name, no datasheet)
What I'm using is an old compaq 34 pin floppy drive
the connector is a (semi) standard, the folks who make usb floppy drives get standard laptop floppies and repackage them with the controller
it only works with 1.44MB and only for IBM format floppies in MFM format
You couldn't, for instance, read a Mac 800kB mac "GCR" floppy disk
The slim drives in the usb ones are quite noisy and inferior to the full size drives, also the flex cable connector isn't easy to interface for diy.
if you remove the extra board, you can hook into the USB floppy disk with your own controller, like what we've been working on
(or boards like greaseweazel if you can get 'em)
Limor has found that the floppy controller can be flaky, and it's not good at reading damaged diskettes.
But if you have perfect 1.44MB DOS floppies that you want to read, go for it.
One that's important to us is the "Prince Floppy", which is a Mac 800kB floppy. The mac floppy drive could rotate at different speeds, and stored a varying amount of data on each track. That's how they stored 800kB when DOS could only store 720.
I've read 720KB MFM disks with USB floppy drives just fine.
we posted the contents of the prince floppy here - https://archive.org/details/prince_floppy
Question: Have you been able to identify the chip on those usb drives? If its a mcu it would be nice to reprogram it with a firmware which can read at fluxlevel.
Q: Are there any places/people making *new* floppy drives/disks? How difficult would it be to make a floppy disk?
@Nick Tonn No, Limor didn't successfully identify the chip
cli tool was mentioned?
you cannot reprogram it - its almost certainly an asic
@Nick Tonn they said it's an ASIC
Could the fluxlevel thing be done with an oscilloscope? DS1054Z has 20 megs of RAM. 20 megasamples.
Those were optical right? The sector sensors, I mean
I think you could, you can download the full trace within the DS1054Z using USB or network .. you'd have some coding to do!
@PixelDud you can buy new floppies, I know because some medical devices still use them
it costs a lot and takes a lot of time to certify a new medical device
Chris Fenton's Cray archaelogy is relevant to the flux-level issues.
@deʃhipu cool, do you know the brand of them?
@anfractuosity no, sorry
Dan, 8" had hard- and soft-secto
@Dan Maloney yes they're optical on 5.25s at least, we're actually debating about 3.5 since there's no visible hole
I thought that was a drive sprocket on the 3.5"
This shugart interface is basically the same all the way back to 8" drives, isn't it? It should be do-able to image thoae drives almost exactly the same way, right?
you can buy sealed packs of floppies on ebay
@limor are they NOS though?
it's where it grabs, so it also knows the position
Yeah, that makes sense
Sorry. Older discs (8 and 5.25) came in two variants some with one index pulse/hole per revolution and some with one pulse/hole per sector.
I doubt its an asic, if it was an asic, there would be no reason for the asian manufactures to sand down the markings on the chip. Also i've seen usb-floppy pcbs with an unpopulated place for flash memory.
@deʃhipu ah yeah that makes sense now
it didn't at first
the 3.5" floppies have that tab to which the rotor grabs. I think it can be synced to the physical position of the rotor itself.
Is it like a legacy thing?
Index pulse needed to get the formatting right: all the tracks aligned.
Does the DD floppy's read both sides at the same time when reading data
yes
Will: no. Side-select signal
or do you mean parallel, then no
DD is double density - it how close the magnetic flux pulses can be written/read
The apple II did calibrate the speed based on the motor control chip. It was a Shugart SA400 drive with a custom analog board.
I have only seen double sided reading drives was in IBM land, older apple drives you had to manually flip the disc and put it back in to read the other side.
DS is doublesided - theres' two 'heads', top and bottom
and you select which you want using a digital line
How about the Apple 2 spiral tracks for copy protection
@Will S Merkens that'll be a challenge!
microstepping of the head stepper?
could also help with restoring data from misaligned floppies.
Yeah despite having just ~35-40 tracks, the apple ][ drive can be stepped to about ~160 positions, while a PC drive can only hit ~80 positions
MS flight sim on apple had that protection method and boy the drive sure made horrible sounds
The way an SD card looks to a PC is very much like a floppy - a sequence of 512-byte sectors.
So we re-purposed USB Storage to create an Arduino sketch that can act as a USB floppy drive
could be also done with a raspi zero, in usb gadget mode.
We tested it with the 360k (5.25) drives, try buying a USB 5.25" drive on amazon :wink:
Roman roads developed ruts based on the carts so people in Britain simply based carts and later trains on the same size the ruts in the road were in size
As far as i know does the floppy drive do not care if the data is mfm or gcr encoded, the floppy controller is the part thats cares about the encoding. for example the floppy controller of the Amiga could read and write MFM and GCR encoding with the same floppy drive.
nick - you'd think so but thats not truuuuuuuuuuuuuue :)
could that be done with a DSP? directly interface the head? then we have ALL the encodings we please. software-defined radio works at orders of magnitude above the needed data rates, I think.
playlist here as well, that has 1 min vids from each step / progress - https://youtube.com/playlist?list=PLjF7R1fz_OOWexf2WmY8cgM65ltPaAvyT
Some of the electronics in the floppy are optimized for MFM, in a way that can give problems when you read other formats... if you rip of even more of the electronics, you might be able to fix it(?) but that'd be a lot more work.
I have the Epson SMD1300 looking for tech docs on what it can do.
Very short & very long pulses that exist in the mac format can't be read because of details of the on-drive electronics
sony drives work pretty good though
I'm psyched about this work. I have code I wrote in college on some floppies. I implemented RSA encryption when I was a senior in '86 when I was a C newbie and ran it on a Vax 11/780 (yep VAX MIPS are based on this machine). I'd really like to see how fast it runs on an my M1 Mac Mini.
+! for tee-ack
The best day to copy your data off a floppy is today
yesterday
Ha, I think you folks are calling me old.
"how long is the data likely to be good" ? ...
Old is relative.
"baking" the disks to make them work for a while, is it tested? I have seen it mentioned about audio tapes
I stored all my 5.25 in floppy boxes and those are stored away
what would currently be the most durable format for storing data at home?
how does the stored signal degrade? can the oscilloscope approach give better chances of recovering old data?
cdrs tend to disintegrate too
Baking will only work if the problem is water adsorbtion into the Mylar. It is likely to make things worse if the oxide is starting to come off.
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