Although you can do basic floating point format operations like addition and subtraction just fine on any CPU, having specialized hardware for it can provide a significant speed boost. Here Intel’s 8087 was the first mainstream floating-point coprocessor to provide this option to a wide audience, with [Ken Shirriff] recently reverse-engineering using an 8087 die how these basic operations were implemented.

The real-world speed-up of even simple operations like adding two floating point numbers compared to the 8086 CPU was on the order of a hundred times, which is very relevant the moment you start doing interesting things with spreadsheets, not to mention rendering 3D scenes in CAD software or even games.

As always, the devil is in the details, with sneaky infinities and edge cases also providing the biggest potential for speed-ups in dedicated silicon, along with the large circuitry spent on the shifter. With floating point values being very much about aligning values with shifting by a number of bits, this circuitry along with the detecting of over- and underflows is the key element why the 8087 and its successors were so crucial in making floating-point operations at all feasible in PC applications.

How this shifting works in theory is detailed in the article by [Ken], along with how the 8087 implements this in its circuits. Naturally, a large part of this is implemented in microcode, the listing for which is also provided. From this it’s quite clear how what seems like a simple set of operations is actually quite complex, making even the now much maligned x87 ISA an improvement over doing it all in integer-based software.

YouTube, like the Internet, has its plusses and minuses. On the plus side, you can find information on just about anything. On the minus side, you don’t always know if that information is of any value. On the plus side, you can connect to experts who have an uncanny knack for explaining things. On the negative side, you can find people who — let’s just say aren’t. Lucky for us, [Kerry Wong] is very knowledgeable about test instruments, so when we see a review from him, like the one for the ZOYI ZT-XC1 LCR meter and multimeter, we know we will get good information. Check out that review in the video below.

It used to be unusual to have an LCR meter that could measure inductance or capacitance in a home lab. But now it isn’t a big deal, and many multimeters and testers can at least attempt to read these quantities.

[Kerry] noted that the charging port is on the back, which is not very handy, but he also points out it isn’t a showstopper. Oddly, in multimeter mode, the device won’t read capacitance or current, so that makes it less handy as a multimeter.

One of the limitations of many capacitance measurement meters is that they can’t easily account for the capacitance of the test leads. This meter has two adapters that plug into the front of the meter for LCR measurements. That’s great, as long as what you want to measure fits into one of those adapters. If not, then you are out of luck. One adapter fits through-hole components, and the other one is a clever jig for holding surface-mount parts.

We always enjoy listening to [Kerry] talk about oscilloscopes. He even dabbles in reviewing test clips.

In a world where wireless earbuds are increasingly seen as devices that you toss into the e-waste bin as soon as they stop working, it’s heartening to see companies take the opposite approach with their designs. In a recent teardown of the new Fairbuds 2 by [iFixit] we get a blow-by-blow report of disassembling one of these devices, getting to its rechargeable LIR1054 coin cell, as well as the very accessible PCB should you have to replace a shorted capacitor or similar issue.

Much like with the first version, the 3.6 V lithium-ion coin cell can be extracted simply by pulling on the battery door, which leverages it out of the enclosure. Despite this easy access method and no glue these earbuds are still IP54 rated, so they’re safe to wear when you’re dashing for shelter in a sudden downpour.

To get further into the device, you have to overcome the plastic clips that hold the enclosure together, along with what appears to be a few dabs of glue. Inside it you find the PCB containing the guts, including the Airoha AB1577S, Cortex-M4F-based IC that provides the Bluetooth Low Energy capabilities as well as enabling the touch control and other features.

Below the PCB is the coin cell holder, followed by the only part that saw real glue usage, namely the driver section. Presumably this is the compromise to keep things like sweat out of the device. Even so, after disassembly [iFixit] managed to reassemble the device and the earbud remained in working condition.

The case for the earbuds is even easier to disassemble, using just some bolts to unfasten. The USB-C port is soldered to the PCB which [iFixit] dinged them on, but still gave it a 10/10 on their repairability score.

Compared to Apple’s AirPods this is obviously a whole different world, although recently [iFixit] was somewhat pleased with the most recent AirPods generation being slightly more repairable, with non-destructive entry for a battery swap at least somewhat feasible.

Recently [Ken Shirriff] got handed a mystery IC by [CuriousMarc] who had found said IC in a box of various old chips. Labelled only with a date code of the 47th week of 1985 and a mysterious F1-10-5 alongside a logo that didn’t lead to any hits in the typical IC databases, it was up to [Ken] to figure out what lurks inside this CDIP chip.

As it turns out, it’s actually a pretty interesting IC with an easy to identify die once the ceramic package had been cracked open with a surgical hammer-and-chisel strike.

With the die under a microscope it was identified as a Harris HF10, itself a variant of the National Semiconductor MF10. This is a dual switched capacitor filter, with the modern version being e.g. the TI MF10-N in both PDIP and SOIC, but sadly no CDIP any more. Availability seems scarce, so the MF10 may not be long for this world.

These filter ICs can tune their capacitors to act as a low-, band- or high-pass filter. How this works is explained by [Ken], with switched capacitors replacing the resistors of a typical filter circuit. The main reasons for doing this over just using a resistor include how large resistors can get compared to the relatively small capacitor, not to mention their fixed value versus the adjustable resistance from the switchable capacitor.

The remainder of the circuit is mostly there to enable the switching and overall operation, providing a fascinating glimpse at a chip that would have been incredibly useful in the 1980s, including in synthesizers where this adjustable filter feature was most convenient.