DEC microVAX with tape drive

Bake It To ReMake It: Cooking Old Magnetic Tape To Recover Data

Those of us old enough may remember the heyday of the text adventure game genre from the first time around. London-based Magnetic Scrolls was an early pioneering company producing titles for the first Amiga and Atari ST platforms. Fast-forward to 2017 and [Hugh Steers], the original co-founder and core developer for Magnetic Scrolls has formed an initiative to revive and re-release the original games on modern platforms. Since the 1980s-era DEC MicroVAX used originally for development is not particularly rare in retro computing circles, and media containing source code was found in someone’s loft space, reviving the games was not a tall order.

First, he needed to recover a copy of the original source code from the backup tapes. But there was a problem, it turns out that the decaying tapes used a unstable polyurethane-based binder to stick the oxide material (which is what stores the data) to the backing tape, and this binder can absorb water over the years.

Not much happens until you try to read the tape, then you trip over the so-called sticky-shed syndrome. Secondly you may find that a small amount of the oxide layer sheds from the tape, coating the read head, rollers and guides inside the complicated tape mechanism. This quickly results in it gumming up, and jamming, potentially chewing up the tape and destroying it permanently.

This was further exacerbated by the behaviour of the DEC TK50Z tape drive, which needed to shuttle the whole length of the tape as part of its normal operation.

A temporary solution was to bake the tape in an oven to drive out the moisture and reduce the stickiness enough to run it through the drive safely. Then only the oxide-shedding problem remained. The TK50Z drive was swapped for a TZ30 which shuttles the tape less, but also critically with a simple hack, would allow the heads to be cleaned with IPA between read passes. This was enough to keep the gumming up at bay and allow enough data to be read from the tapes to recover several games worth of code, ready for the re-releasing process.

The video after the break shows [Rob Jarratt] working through the process of the data recovery.

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Reading Floppies With An Oscilloscope

There’s a lot of data on magnetic media that will soon be lost forever, as floppies weren’t really made to sit in attics and basements for decades and still work. [Chris Evans] and [Phil Pemberton] needed to read some disks that reportedly contained source code for several BBC Micro games, including Repton 3. They turned to Greaseweazle, an interface board that can dump just about any kind of floppy disk if it is attached to the right drive. The problem is that Greaseweazle couldn’t read the disks due to CRC errors. Time to break out the oscilloscope and read the disk manually, which is what they did.

Greaseweazle provides a nice display of read sectors and shows timing coming from the floppy read head. The disk in question looked good with reasonably clean timing clocks except in the area of one sector. At that point, the clocks degenerated into noise. Looking on the disk, it was easy to see why. The actual media had a small dent in it.

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Reconstructing Data From A Corrupt Apple ][ Floppy Disk

Back in 1990 [Benjamin Zotto] wrote – while in elementary school – a dog racing game called Wonderland 2. The BASIC source code and images for the game were stored on a single ProDOS formatted, soft-sectored 5.25″ floppy disk. Fast-forward thirty years to today and [Benjamin] found to his dismay that ProDOS could no longer read the floppy, giving an I/O error. Not deterred, he set about to recover the data, as documented in this Twitter thread.

Applesauce visualization of the patterns on the corrupted disk, with soft-sectoring spiral arms.

The gist of the story is that the floppy disk’s surface could still be scanned with help from the aptly named Applesauce Floppy Drive Controller, which got the following visualization of the magnetic patterns on the disk surface:

This data could then be analyzed sector by sector, with the bad sectors and the cause for ProDOS flaking out with its reading attempts here marked in red.

Checking the data recovered so far confirmed that it was a ProDOS disk. It also confirmed that the sector containing the directory listing was shot. This required diving into the technical reference manual for ProDOS and its filesystem to figure out how to reconstruct the directory layout. This required figuring out the offsets and sizes of the files, assisted by knowing what was likely on the disk, and having some bits and pieces of the original volume listing still intact. This allowed for the directory volume to be rebuilt, one byte at a time.

Sectors on the disk, with bad sectors in red.

At the end of that arduous and highly educational journey success waited, and [Benjamin] was once again able to relive his memories of 1990s BASIC and hand-drawn bitmap graphics.

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Hackaday Links: January 5, 2020

It looks like the third decade of the 21st century is off to a bit of a weird start, at least in the middle of the United States. There, for the past several weeks, mysterious squads of multicopters have taken to the night sky for reasons unknown. Witnesses on the ground report seeing both solo aircraft and packs of them, mostly just hovering in the night sky. In mid-December when the nightly airshow started, the drones seemed to be moving in a grid-search pattern, but that seems to have changed since then. These are not racing drones, nor are they DJI Mavics; witnesses report them to be 6′ (2 meters) in diameter and capable of staying aloft for 90 minutes. These are serious professional machines, not kiddies on a lark. So far, none of the usual government entities have taken responsibility for the flights, so speculation is all anyone has as to their nature. We’d like to imagine someone from our community will get out there with radio direction finding gear to locate the operators and get some answers.

We all know that water and electricity don’t mix terribly well, but thanks to the seminal work of White, Pinkman et al (2009), we also know that magnets and hard drives are a bad combination. But that didn’t stop Luigo Rizzo from using a magnet to recover data from a hard drive. He reports that the SATA drive had been in continuous use for more than 11 years when it failed to recover after a power outage. The spindle would turn but the heads wouldn’t move, despite several rounds of percussive maintenance. Reasoning that the moving coil head mechanism might need a magnetic jump-start, he probed the hard drive case with a magnetic parts holder until the head started moving again. He was then able to recover the data and retire the drive. Seems like a great tip to file away for a bad day.

It seems like we’re getting closer to a Star Trek future every day. No, we probably won’t get warp drives or transporters anytime soon, and if we’re lucky velour tunics and Spandex unitards won’t be making a fashion statement either. But we may get something like Dr. McCoy’s medical scanner thanks to work out of MIT using lasers to conduct a non-contact medical ultrasound study. Ultrasound exams usually require a transducer to send sound waves into the body and pick up the echoes from different structures, with the sound coupled to the body through an impedance-matching gel. The non-contact method uses pulsed IR lasers to penetrate the skin and interact with blood vessels. The pulses rapidly heat and expand the blood vessels, effectively turning them into ultrasonic transducers. The sound waves bounce off of other structures and head back to the surface, where they cause vibrations that can be detected by a second laser that’s essentially a sophisticated motion sensor. There’s still plenty of work to do to refine the technique, but it’s an exciting development in medical imaging.

And finally, it may actually be that the future is less Star Trek more WALL-E in the unlikely event that Segway’s new S-Pod personal vehicle becomes popular. The two-wheel self-balancing personal mobility device is somewhat like a sitting Segway, except that instead of leaning to steer it, the operator uses a joystick. Said to be inspired by the decidedly not Tyrannosaurus rex-proof “Gyrosphere” from Jurassic World, the vehicle tops out at 24 miles per hour (39 km/h). We’re not sure what potential market for these things would need performance like that – it seems a bit fast for the getting around the supermarket and a bit slow for keeping up with city traffic. So it’s a little puzzling, although it’s clearly easier to fully automate than a stand-up Segway.

Hard Drive Data Recovery – Why Not DIY?

Hard drive failures can be tough to bear, particularly for the average person who doesn’t back up. When it comes to data recovery, there’s always those bleating from the sidelines that it’s a job that must be left to the professionals. However, this is Hackaday, not HireSomeoneADay, so [Matt]’s video on do-it-yourself hard drive repair is just what we like to see.

The video begins with plugging the non-functional drive into an external caddy, and using a microphone to listen to the sounds it makes. Upon analysis, [Matt] concludes that the drive is not spinning up, and suspects the heads may be stuck, causing the problem. When tapping the drive fails to unstick the heads, the next step is disassembly.

Despite the best advice from armchair commentators, this can be achieved at home without a clean room. [Matt] opens the drive carefully, and notes that the head is indeed stuck to the platter, instead of sitting in its home position. Using a screwdriver, the platters are rotated in their usual direction while gentle pressure is applied to pull the head away, being sure to use a light touch to avoid ripping the heads off entirely. With this done, the drive is reassembled and powered up. Amazingly, the repair is successful, and data is able to be recovered!

It’s important to note that this is a highly risky procedure, and not guaranteed to succeed. Truly valuable data should be left to the professionals, but if you’re skint or simply unbothered, it doesn’t hurt to have a go yourself. Be sure to avoid dust entering the drive, and take care not to touch the platters themselves. Of course, if you brick the device, you can always scavenge it for parts. Video after the break.

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Soldering Saves Data From Waterlogged Laptop

What happens when you drop your laptop in the pool? Well, yes, you buy a new laptop. But what about your data. You do have backups, right? No, of course, you don’t. But if you can solder like [TheRasteri] you could wire into the flash memory on the motherboard and read it one last time. You can see the whole exploit in the video below.

There’s really three tasks involved. First is finding the schematic and board layout for motherboard. Apparently, these aren’t usually available from the manufacturer but can be acquired in some of the seedier parts of the Internet for a small fee. Once you have the layout, you have to arrange to solder wires to the parts of the flash memory you need to access.

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EMMC To SD Hack Rescues Data From A Waterlogged Phone

How do I get the data off this destroyed phone? It’s a question many of us have had to ponder – either ourselves or for friends or family. The easy answer is either spend a mint for a recovery service or consider it lost forever.  [Trochilidae] didn’t accept either of those options, so he broke out the soldering iron and rescued his own data.

A moment’s inattention with a child near a paddling pool left [Trochilidae’s] coworker’s wife with a waterlogged, dead phone. She immediately took apart the phone and attempted to dry it out, but it was too late. The phone was a goner. It also had four months of photos and other priceless data on it. [Trochilidae] was brought in to try to recover the data.

The phone was dead, but chances are the data stored within it was fine. Most devices built in the last few years use eMMC flash devices as their secondary storage. eMMC stands for Embedded Multimedia Card. What it means is that the device not only holds the flash memory array, it also contains a flash controller which handles wear leveling, flash writing, and host interface. The controller can be configured to respond exactly like a standard SD card.

The hard part is getting a tiny 153 ball BGA package to fit into an SD card slot.  [Trochilidae] accomplished that by cutting open a microSD to SD adapter. He then carefully soldered the balls from the eMMC to the pins of the adapter. Thin gauge wire, a fine tip iron, and a microscope are essentials here. Once the physical connections were made,  [Trochilidae] plugged the card into his Linux machine. The card was recognized, and he managed to pull all the data off with a single dd command.

[Trochilidae] doesn’t say what happened after the data was copied, but we’re guessing he analyzed the dump to determine the filesystem, then mounted it as a drive. The end result was a ton of recovered photos and a very happy coworker.

If you like crazy soldering exploits, check out this PSP reverse engineering hack, where every pin of a BGA was soldered to magnet wire.