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The Qiqitori Blogs
Personal blog · blog.qiqitori.com · on HN as qiqitorihardwareprogramming
The Qiqitori Blogs is a personal blog at blog.qiqitori.com about hardware and programming. Since 2021, 4 different Hacker News readers have linked it 25 times, most often “Implementing "Tennis for Two" using op amps (2024)”. It is still writing: the last post was on 2026-01-14, and you can follow it by feed.
25mentions?
4HN people?
2021–2026first – last linked?
Most-linked posts?
- Implementing "Tennis for Two" using op amps (2024)2 people · 5 mentions · first linked 2024-08-21
What Hacker News says?
> I try a bunch of different OCR programs, but can't find any that can transcribe the document with 100% accuracy. They often confuse certain letters or numbers (like 0 and C, 9 and 4, 0 and D). Sometimes they omit characters, sometimes they introduce new ones. I try different font sizes and different fonts, but it doesn't matter. I decided to OCR a hex dump from an old computer magazine a while back and fixed this…
Comment linking /2023/03/ai-day-in-retroland-prolog-on-the-commodore-vic-20-needs-expanded-ram/
on “How to copy a file from a 30-year-old laptop”Submitted Implementing "Tennis for Two" using op amps (2024) as a story · 37 points
HN discussionAnalog computing, one thing I'm glad I learned a little about! Also made part of the tennis for two game, and occasionally think about adding features. (Course, knowledge of digital electronics keeps interfering. In fact I used two 74-series logic chips in there.) Here's my build log, with everything that makes me cringe after a few years left in tact: https://blog.qiqitori.com/2024/08/implementing-tennis-for-tw...
Comment linking /2024/08/implementing-tennis-for-two-using-op-amps/
on “Ask HN: What are you reading?”Submitted Tiny aquarium fish net 3D print as a story · 2 points
HN discussionOn the topic of analog computers, I recently decided to explore the topic a bit and built something similar to "Tennis for Two" (one of the first video games) on a single breadboard using op amps and relays: https://blog.qiqitori.com/2024/08/implementing-tennis-for-tw...
Comment linking /2024/08/implementing-tennis-for-two-using-op-amps/
on “Basic Mechanisms In Fire Control Computers (1953) [video]”Submitted Decoding Docker's Local-Kv.db as a story · 1 points
HN discussionYes, agreed. I lived in Matsue a couple years ago and found a couple nice spots that were covered in ocean trash. Loads of plastic bottles both from Japan and other countries (there was a milk carton from Australia), styrofoam, polyester apparel, some random other stuff. Pic: https://blog.qiqitori.com/wp-content/uploads/2017/08/DSC0249... Boring blog entry: https://blog.qiqitori.com/2017/08/beach-cleaning-in-matsue-…
Comment linking /2017/08/beach-cleaning-in-matsue-japan/
on “The recycling myth: A plastic waste solution littered with failure”A while ago I was a little into controller hardware hacking and did almost the same thing but for an MSX! Even wrote a blog entry, but unfortunately in Japanese (with pictures though): https://blog.qiqitori.com/2022/09/%E6%9D%90%E6%96%99%E8%B2%B... And one year later I also used a Raspberry Pi Pico to convert a USB controller's signals to MSX: https://blog.qiqitori.com/2023/09/using-a-usb-hid-game-contr... (And late…
Comment linking /2023/09/playing-on-the-nintendo-switch-with-a-generic-usb-hid-controller-specifically-a-fake-ps3-controller/
on “Building a USB SNES Controller”Last year when I did a lot of sound-related projects, I implemented the YM3012 DAC on a Pico: https://blog.qiqitori.com/2023/03/raspberry-pi-pico-implemen... I used PIO to read the digital input and used PWM for the sound output. I verified that the conversion was correct but unfortunately never really put in a lot of effort to try to make it sound good. There's a bit of a hiss.
Comment linking /2023/03/raspberry-pi-pico-implementation-of-the-ym3012-dac-mono/
on “Playing audio files in a Pi Pico without a DAC”Hey, I made something like this a couple months ago! (Except it's more like "Tennis for Two", so you also hit the ball in the X direction, and there's another button to hit it back in the other. I didn't have any space or potentiometers left to set the gravity, but it wouldn't be difficult.) I also learned heaps! (Including after a few weeks when the circuit stopped working properly because one of the relays started…
Comment linking /2024/08/implementing-tennis-for-two-using-op-amps/
on “The Analog Thing: Analog Computing for the Future”I recently replaced a broken DRAM chip on one of those! https://blog.qiqitori.com/2022/02/testing-a-zx81-ram-pack-wi... (this is more about finding which one is the broken one than about the actual replacement) The one I had doesn't seem very wobbly though. Maybe there is some variation between production runs etc.?
Comment linking /2022/02/testing-a-zx81-ram-pack-with-an-arduino/
on “March 5, 1981: Timex Sinclair ZX81 Launched (2018)”The ZX80 is another old computer that can be made very close to the original ( there are no special chips inside, and most of them are still being manufactured. The DIP version of the Z80 CPU is famously no longer being manufactured since last year and the RAM chips probably aren't either, but there's no shortage of new old stock for both). If you want to make your own: http://searle.x10host.com/zx80/zx80.html My bu…
Comment linking /2024/03/building-a-new-zx80/
on “Classic Computer Replicas”I "preserved" a (probably somewhat lost) sokoban-like game (from the makers of Sokoban in fact) from the early 1980s as a JavaScript game about a year ago. https://blog.qiqitori.com/tnt_bomb_bomb/ Check it out if you're interested. * "probably somewhat lost" as in, not available as a ROM/image anywhere on the internet AFAICT, but some mentions, and even gameplay videos on YouTube
Comment linking /tnt_bomb_bomb/
on “Arctic Adventure: A Lost 1981 TRS-80 Adventure Game”I do some retro work, and in order to debug a system (this was at a time when I knew less about this type of system) I once plugged in a Raspberry Pi Pico into a Z80 socket (not directly of course) and ran commands to read/write from/to memory/IO/ROM to see if I could find the problem. Makes you feel quite omnipotent :) Course, my setup didn't really emulate the Z80 to run code, it just emulated its signals for a ha…
Comment linking /2023/02/two-raspberry-pi-picos-pretending-to-be-a-z80/
on “Debugging hardware is hard”The ZX Spectrum has this sound chip (or almost, for the pedants) and there's a lot of interesting music composed for it. Mostly from Eastern Europe apparently? Here's a good selection: https://zxart.ee/eng/music/top-100/ (I had a bunch of time last year and learned a lot about some retro sound chips, including this one, and while at it converted two tunes I liked to MSX ROMs, as I have an MSX and the sound chip is t…
Comment linking /2023/05/playing-psg-tunes-or-even-asc-pt3-tunes-on-the-msx-part-2/
on “Fourays: A Tribute to the AY-3-8910”The RP2040's PIO is awesome. Here are two retro-related projects I did in the last ~year. You can capture video in a weird format with PIO on one core, and output it with PIO (in a standard format like VGA, or even DVI) on the other core, like here: https://blog.qiqitori.com/2022/09/raspberry-pi-pico-15-6-khz... Or you can implement old DACs that expect a weird input data format, to a certain extent, like here: http…
Comment linking /2023/03/raspberry-pi-pico-implementation-of-the-ym3012-dac-mono/
on “Recreating RP2040 PIO Interface in an FPGA”I built a basic version of Tennis for Two a while back, using regular op amps. Some modern oscilloscopes have bad X-Y mode implementations, but most non-extremely-cheap scopes are probably decent enough. https://blog.qiqitori.com/2024/08/implementing-tennis-for-tw... I'm also planning on selling a kit in the near future!
Comment linking /2024/08/implementing-tennis-for-two-using-op-amps/
on “The First Video Game Came Long Before Pong”We are at an interesting point in computer history IMO. Microcontrollers are getting fast enough to keep up with most things happening inside the first (or first few) generations of personal computers. Before, you had to use FPGAs. Now, people use the Pico to create things like digital RGB upscalers or N64 cartridges. The Raspberry Pi Pico is fast enough (or almost fast enough) to keep up with most timing transition…
Comment linking /2023/08/testing-4164-4116-dram-ics-in-circuit-live-with-a-raspberry-pi-pico-without-removing-them-wip/
on “Reverse-engineering the classic MK4116 16-kilobit DRAM chip”Two days late, but as there have been a few submissions about compilations of the blogs featured in the comments attached to this post, I guess I might as well throw in mine too. https://blog.qiqitori.com Mostly retro stuff, but not always. In fact, the next post won't really be about retro I think!
Comment linking /
on “Ask HN: Could you share your personal blog here?”I once wrote a tool that helps with finding mistakes in OCR'd fixed width text, https://blog.qiqitori.com/2023/03/ocring-hex-dumps-or-other-... Basically it just clusters same characters and asks the human to find the problems, which is easy when you're looking at a series of pictures like ssssss5sss. The UI is kinda least-effort. Should ask a modern AI agent to make it look nice and intuitive, sometime maybe.
Comment linking /2023/03/ocring-hex-dumps-or-other-monospace-text-and-verifying-the-result/
on “Decoding the obfuscated bash script on a Uniqlo t-shirt”