For the final day of #DOScember 2025 here is part 4 of my #IBM5150 restore series. With lots of help from the community, I try to trace down what IC(s) are keeping the board from booting. Happy Janky New Year! IBM 5150 will return! youtu.be/p_PW85AOUFg #RetroComputing #VintageeComputing #IBMPC

Intel announced the 8087 floating-point chip in 1980. Now I have a blog post that explains a small part of the microcode in this chip. www.righto.com/2025/12/8087...

love me some CRTC abuse

Here are the DOS game trivia quiz questions I made for an event earlier in the month: youtu.be/z3mGQgVXkp8 They are all pre-Wolfenstein-3D, but most have some sort of visual clue to help out. Let me know your score :-)

Yes, thank you Bluesky, I can clearly see the similarities.

I've released my tool for encoding pixel art on floppy disk tracks. Because that is surely a thing that people will want to do? I don't know. I just get ideas and dumb stuff happens. github.com/dbalsom/flux... #retrocomputing #floppy #floppydisk

I was honored to participate in the annual Big Red Arrow Club Christmas Trivia Quiz this year, not only did I participate on a team, but had a lot of fun creating questions for the other team. After the holidays, I'll post my question block at max quality for everyone else to test their DOS skills.

🎥 New #IBM5150 Video Drop 🎞️ In Part 3 of my IBM 5150 restoration series for #DOScember, I check for the 4.77MHz clock signal on the motherboard and give it a ultrasonic bath. (Sorry about the choppy audio, not sure what went wrong.) youtu.be/pedaVnDbGm0 #IBMPC #VintageComputing #RetroComputing

i would pay disgusting amounts of money for a floppy quilt

Appreciate you. The Retro and Vintage community is so welcoming and amazing. 🙏🏻

Posting here alongside my Mastodon ([email protected]), the Seequa Chameleon also allows for customized CGA color palettes via an OPTION program! Here is Alley Cat running in red white and blue, straight from composite! #seequa #retrocomputing

Did you know the 1982 Seequa Chameleon could save BIOS configurations via a DOS program? If you’re thinking it did so via a button battery, you’d be wrong! The Chameleon used this dinky XD2210 64x4 NOVRAM memory chip to store it! Thanks to @gloriouscow.bsky.social for finding this!

Having a digital simulation of the CGA card can be very educational. Here's a screenshot from the game ZZT, which is obviously in text mode: #retrocomputing

My digital logic simulation of the IBM CGA now has color! And a release! github.com/dbalsom/cga_... #retrocomputing

A lot more progress on the IBM CGA logic simulation. We have VRAM, and font ROM, CAS/RAS RAM timings, the shift/load clock, character glyph shift register, and somehow it all works?? Still do do: text mode attributes, and all of graphics mode... #retrocomputing

so many all-women teams! every time I read about this, I discover new names and firsts. some of these women were developing machines from scratch to change the world for pennies per hour, got harassed daily, then went home to take care of multiple children in the evenings. I simply cannot fathom.

Some of the "new-style" CGA cards have this bodge wire, in a classic IBM yellow. But what is it for? #retrocomputing

Successfully dumped the ROMs from this absolutely disgusting Seequa Chameleon motherboard. You can see how clean it was *supposed* to be, underneath. Turns out it was a version with no prior good dump, so that's cool! @mcjonestech.com #retrocomputing

nand2mario has made this awesome 8086 microcode browser: nand2mario.github.io/8086_microco... #retrocomputing

More progress on the CGA. Most of the visible traces are in - I've been running some traces on 2nd layer - I have no idea how they actually run, but hey, you can't see them anyway.

The PCB of the IBM CGA card is translucent, at least where there are no copper fills or solder mask. That mostly means the areas around the pads. If you hold the card up to the light, you can see all the pads glow. #retrocomputing

🎄🎅🏼🎥 #DOScember Video Drop 🎞️ This year for DOScember I give you the gift of me fumbling around inside an #IBM5150 PC as I try to restore it to working condition all month long. youtu.be/Jlaypmy0PyY #IBM #VintageComputing #RetroComputing

Day 2 of tracing out the IBM CGA card. I had vivid dreams last night, all in cyan and magenta.

At some point, IBM redrew the traces for the IBM CGA card - there were originally lots of 90 degree angles, the new version is all smoother 45 degree angles. This change happened after the redesign of the CGA's composite output, as there are so-called "new style" CGA's with the 90 degree traces.

Now live on my site: an after-action report and analysis of Inherit the Earth: Quest for the Orb. Thankfully, you won't have to navigate a maze to reach it, something I wish could be said about parts of the game ;o; Hope you enjoy reading, and shares appreciated <3

Has anyone ever successfully put the metal shutter back on a 3.5" floppy disk after taking it off?

Everyone talks about hard disks and floppy disks, while the medium firmness disk is completely forgotten

New project: ImAnim "Animation Engine for Dear ImGui" by @soufianekhiat.bsky.social - Repo github.com/soufianekhia... - Post github.com/ocornut/imgu...

Tracing out the PCB for the IBM CGA card in KiCad. #retrocomputing

Here's a visualization of the EGA's VRAM data bus. Each graphics controller controllers two planes, and has a 16-bit data path to do so, letting the EGA read all four planes at once, which is nice. #retrocomputing

My little SVG is famous now!

Something about pin-conditional jump instructions pleases me.

I've uploaded my IBM 5150 motherboard illustration to Wikimedia. Free to use under CCA-SA 4.0 commons.wikimedia.org/wiki/File:IB...

The IBM 5150 motherboard, illustrated. #retrocomputing

I'm very excited about C++26 reflection. However, people underestimate what you can achieve *today*! Inspired by Barry Revzin's awesome "Practical Reflection" talk at @cppcon.bsky.social I wrote automatic Dear #imgui generation for structs, including labels! (via Boost.PFR) #cpp #gamedev

Hard disks are floppy at sufficient temperature

Orienting a RigidBody with precision timing requires something beyond a naïve "accelerate-towards-target" method. Here's a slow-motion comparison between the naïve method vs. what I call the "Akira slide". Green line indicates acceleration. #GodotEngine #gamedev #indiedev

Writing my own disk drive cleaning program today because I don't like how other programs do it. (Mine uses a butterfly pattern, and only runs for 20 seconds, because that should be long enough to unjam any gunk from the heads.)

It's official! #PicoIDE, the open source IDE/ATAPI drive emulator I've been working on for the better part of this year, will be launching at Crowd Supply! Go there to sign up for updates and to be notified when the campaign is live: www.crowdsupply.com/polpotronics...

More MOO-related pixel art

Rednex's publisher has decided that me playing their game, which included 10 seconds of their music in-game, was not "fair use." Even though it quite clearly is. Another case of YouTube's copyright system being absolutely broken as fuck. I have no choice but to relinquish monetization of that video.

flux cats #retrocomputing

Don't copy that floppy. It says so. #retrocomputing

From Infoworld, July 1983. My guy generated SIX FEET of code. How many feet of code did you write today? #retrocomputing

I've officially released my real-mode emulator CPU test suite for the Intel 80386. github.com/singlestepte... #retrocomputing #emulation

Disassembly (+ comments) of tape protection of Repton (Acorn Electron). Interesting protection measures. Hidden data in tape block headers is my favourite trick github.com/0xC0DE6502/t...

A rare example of Vault Corporation's "PROLOK" copy protection scheme on a 3.5" floppy disk. Vault used some method - probably a laser - to remove the oxide coating from one side of the mylar disk, making it impossible to write to. #retrocomputing

I used to watch/research up to 10 hours of video on YouTube every single day -- but I spent less than 10 hours doing it. I just released a video where I document all of my YouTube viewing speedhacks I've figured out over the years: youtu.be/B1yHK_nEKaM

Before I got deep into the retro computing hobby, I dabbled in watercolors. My art desk is now an electronics workstation cluttered with equipment and various Arduino projects. I kinda miss painting though. I wish I had the space to have both hobbies. #watercolor

made a lil mascot for my MOO-format for emulator CPU tests i've always done pixel art in photoshop but maybe i should try aseprite someday