Labelled die of the Ramtron FM24C64 FeRAM chip. (Credit: Ken Shirriff)

Inside A 1999 Ramtron Ferroelectric RAM Chip

Structure of the Ramtron FeRAM. The image is focus-stacked for clarity. (Credit: Ken Shirriff)
Structure of the Ramtron FeRAM. The image is focus-stacked for clarity. (Credit: Ken Shirriff)

Although not as prevalent as Flash memory storage, ferroelectric RAM (FeRAM) offers a range of benefits over the former, mostly in terms of endurance and durability, which makes it popular for a range of (niche) applications. Recently [Ken Shirriff] had a look inside a Ramtron FM24C64 FeRAM IC from 1999, to get an idea of how it works. The full die photo can be seen above, and it can store a total of 64 kilobit.

One way to think of FeRAM is as a very small version of magnetic core memory, with lead-zirconate-titanate (PZT) ferroelectric elements making up the individual bits. These PZT elements are used as ferroelectric capacitors, i.e. the ferroelectric material is the dielectric between the two plates, with a positive voltage storing a ‘1’, and vice-versa.

In this particular FeRAM chip, there are two capacitors per bit, which makes it easier to distinguish the polarization state and thus the stored value. Since the distinction between a 0 and a 1 is relatively minor, the sense amplifiers are required to boost the signal. After a read action, the stored value will have been destroyed, necessitating a write-after-read action to restore the value, all of which adds to the required logic to manage the FeRAM. Together with the complexity of integrating these PZT elements into the circuitry this makes these chips relatively hard to produce and scale down.

You can purchase FeRAM off-the-shelf and research is ongoing, but it looks to remain a cool niche technology barring any kind of major breakthrough. That said, the Sega Sonic the Hedgehog 3 cartridges which used an FeRAM chip for save data are probably quite indestructible due to this technology.

Fixing A Busted Fluke While Fighting A Wonky Schematic

Fluke meters have been around for a long, long time. Heck, we’ve got a Fluke 73 that we bought back in 1985 that’s still a daily driver. But just because they’ve been making them forever doesn’t mean they last forever, and getting a secondhand meter back in the game can be a challenge. That’s what [TheHWCave] learned with his revival of a wonky eBay Fluke 25, an effort that holds lessons for anyone in the used Fluke market.

Initial inspection of the meter showed encouragingly few signs of abuse, somewhat remarkable for something built for the military in the early 1980s. A working display allowed a few simple diagnostics revealing that the ammeter functions seemed to work, but not the voltmeter and ohmmeter functions. [TheHWCave]’s teardown revealed a solidly constructed unit with no obvious signs of damage or blown fuses. Thankfully, a service schematic was available online, albeit one with a frustrating lack of detail, confusing test point nomenclature, and contradictory component values.

Despite these hurdles, [TheHWCave] was able to locate the culprit: a bad fusible power resistor. Finding a direct replacement wasn’t easy given the vagaries of the schematic and the age of the instrument, but he managed to track down a close substitute cheap enough to buy in bulk. He searched through 40 units to find the one closest to the listed specs, which got the meter going again. Fixing the bent pin also gave the meter back its continuity beeper, always a mixed blessing.

If you’re in the market for a meter but can’t afford the Fluke name, picking up a busted meter and fixing it up like this might be one way to go. But are they really worth the premium? Well, kinda yes.

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Hackaday Links: June 16, 2024

Attention, slackers — if you do remote work for a financial institution, using a mouse jiggler might not be the best career move. That’s what a dozen people learned this week as they became former employees of Wells Fargo after allegedly being caught “simulating keyboard activity” while working remotely. Having now spent more than twice as many years working either hybrid or fully remote, we get it; sometimes, you’ve just got to step away from the keyboard for a bit. But we’ve never once felt the need to create the “impression of active work” during those absences. Perhaps that’s because we’ve never worked in a regulated environment like financial services.

For our part, we’re curious as to how the bank detected the use of a jiggler. The linked article mentions that regulators recently tightened rules that require employers to treat an employee’s home as a “non-branch location” subject to periodic inspection. More than enough reason to quit, in our opinion, but perhaps they sent someone snooping? More likely, the activity simulators were discovered by technical means. The article contains a helpful tip to avoid powering a jiggler from the computer’s USB, which implies detecting the device over the port. Our guess is that Wells tracks mouse and keyboard activity and compares it against a machine-learning model to look for signs of slacking.

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The Secret Behind The Motion Of Microsoft’s Bendy Mouse

The Surface Arc is a designed-for-travel mouse that carries flat, but curves into shape for use. It even turns on when it’s bent and shuts itself off when it’s flat. The device isn’t particularly new, but [Mr Teardown] was a bit surprised at the lack of details about what’s inside so tears it down in a video to reveal just how the mechanism works.

The mechanism somewhat resembles a beaver’s tail, and locks into place thanks to a magnetic connector at the base that holds the device’s shape.

The snap-action of the bending is accomplished with the help of a magnetic connection near the bottom end of the mouse’s “tail”, locking it into place when flexed. Interestingly, the on and off functionality does not involve magnets at all. Power control is accomplished by a little tab that physically actuates a microswitch.

There are a few interesting design bits that we weren’t expecting. For example, there is no mechanical scroll wheel. The mouse delivers similar functionality with touch sensors and a haptic feedback motor to simulate the feel and operation of a mechanical scroll wheel.

[Mr Teardown] finds the design elegant and effective, but we can’t help but notice it also seems perhaps not as optimized as it could be. There are over 70 components in all, including 23 screws (eight different kinds!), and it took [Mr Teardown] the better part of 45 minutes to re-assemble it. You can watch the entire teardown in the video embedded just under the page break; it’s a neat piece of hardware for sure.

If you’re in the mood for another mouse teardown, we have a treat for you: an ancient optical mouse from the 80s that required a special surface to work.

[via Core77]

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Here’s The Norwegian Tape Deck Teardown You’ve Been Waiting For

“They just don’t build ’em like they used to” is a truer statement every year. Whether your vice is CRTs, film cameras, or tape decks, you’ll know that the very best gear simply isn’t manufactured anymore. Even the day-to-day stuff from 60 years ago is often a cut above a lot of today’s equipment. [Anthony Kouttron] shows us this with his teardown of a Tandberg TCD301 from many decades ago.

The Tandberg unit is beautifully finished in wood and metal, a style of construction that’s fairly rare these days. It’s got big, chunky controls, and a certain level of heft that is out of vogue in modern electronics. Heavy used to mean good — these days, it means old. That’s not to say it’s indestructible, though. It’s full of lots of old plastic pulleys and fasteners that have aged over the decades, so it’s a little fragile inside.

Still, [Anthony] gives us a great look at the aluminium chassis and buttons and the electromechanical parts inside. It’s a rats-nest design with lots of discrete components and wires flying between boards. You couldn’t economically produce this and sell it to anyone today, but this is how it was done so many years ago.

This non-functional unit ended up being little more than a salvage job, but we’re still glad that [Anthony] gave us a look inside. Still, if you long for more cassette-themed teardowns, we’ve got the goodness you’re looking for!

Waveform Generator Teardown Is Nearly Empty

We always enjoy [Kerry Wong]’s insightful teardowns, and recently, he opened up a UTG1042X arbitrary waveform generator. Getting inside was a bit of a challenge since there were no visible screws. Turns out, they were under some stickers. We always dislike that because it is very difficult to get the unit to go back together.

Once open, the case reveals it is almost completely empty. The back panel has a power supply, and the front panel has all the working circuitry. The box seems to be for holding the foot and preventing the device from getting lost on your bench.

The power supply is unremarkable. There are a few odd output voltages. The main board is a bit more interesting, especially after removing the heat sink. There are two channels, but the board isn’t laid out, with a lot of segregation between the two channels. That makes sense with the output sections clustered together and the digital section with the CPU, FPGA, and the DAC in close proximity.

The other side of the board connects to a very simple display board. It would be interesting to compare this to a circa-1980s AWG, which would have been far more complicated.

Making a waveform generator with a microprocessor and a DAC isn’t hard. The hard part is the output stages and maximizing the operating speed.

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Voice Control For A Vintage Heathkit Radio

Most modern ham rigs have a voice activated transmission (VOX) mode, although we don’t know many people who use it often. When a transmitter is in VOX mode, it starts transmitting when you talk, and then, when you pause for a second or two, the transmitter turns off. Many old ham transmitters, though, didn’t support VOX, so Heathkit sold the VX-1 “electronic voice control” to add VOX to older transmitters. [Jeff Tranter] shows us inside a clean-looking unit.

These devices were sold from 1958 to 1960 and used tubes and a selenium rectifier. The device is connected between the microphone and the transmitter. It also sat between the receiver and the speaker to mute audio while transmitting. The original unit had a screw terminal to connect to the outside world, and some of the screws had live line voltage on them. The unit [Jeff] examines is modified to have phono jacks along with a few other repairs.

The wiring looks like a tube radio. Tubes are above the chassis, and point-to-point wiring is underneath. There is also an unusual sealed selenium rectifier. [Jeff] shows how the device works using just a receiver. A few minor repairs were needed.

If you are interested in getting your ham license, most modern radios support VOX out of the box — no rhyme intended. We do, however, love that old Heathkit gear.

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