Being pregnant exams was once pretty easy sticks you peed on, however the transfer to digital variations has reworked them into tiny computer systems virtually as highly effective as the unique IBM PC. Fascinated by the digital period of being pregnant exams, Twitter customers foone and xtoff lately pulled aside examples from Walmart and Clearblue to disclose what’s actually occurring inside.
Every take a look at, which prices lower than $5, features a processor, RAM, a button cell battery, and a tiny LCD display to show the end result. The processor is an 8-bit Holtek microcontroller with 64 bytes of RAM, able to working at both 4Mhz or 8Mhz relying on the battery configuration. Which may sound very fundamental, however the chip is surprisingly difficult.
“You might think it’s very limited because it’s only got 64 bytes of RAM, but it’s actually using a pipelined architecture to operate at 1 instruction per cycle, giving it quite good performance for a 4Mhz CPU,” explains Foone in a captivating Twitter thread.
So, with it open, we have got a single PCB right here.
There’s some form of pill-looking factor to the left, a bit of LCD display, and a I can see a battery on the opposite facet. pic.twitter.com/WsuPI3pVsb
— foone (@Foone) September 4, 2020
Foone speculates that this system is “probably faster at number crunching and basic I/O than the CPU used in the original IBM PC.” IBM’s unique PC was based mostly on Intel’s 8088 microprocessor, an 8-bit chip that operated at 5Mhz. The distinction right here is that this can be a being pregnant take a look at you pee on after which throw away.
You would possibly assume that the addition of an LCD display and processor to digitize this being pregnant take a look at improves the accuracy or modernizes how the take a look at works, however that’s definitely not the case. This digital being pregnant take a look at nonetheless features a paper strip to measure the chemical response you create when urinating on the strip.
The paper strip inside acts like a wick so when it will get moist it prompts the battery and powers the system on. The system then makes use of three LEDs and two photosensors to learn the strains on the paper strip that normally present a being pregnant take a look at end result. The processor, RAM, battery, and LCD show actually exist to learn a paper strip and enhance the readability of a take a look at by displaying “pregnant” or “not pregnant” on the show as a substitute of the same old strains that may be tough to learn.
Sadly the chip inside isn’t programmable, so there’s no possible manner folks can get Doom to run on these digital being pregnant exams. I’d advocate studying foone’s full Twitter thread because it’s a captivating teardown. Whereas these digital being pregnant exams look like an unimaginable waste of plastic and electronics, I’m simply grateful humanity has moved on from injecting frogs with urine to confirm pregnancies.