Hacker News: msarnoff

New comment by msarnoff in "Death to Scroll Fade"

msarnoff — Wed, 18 Mar 2026 16:55:23 +0000

Originally read the URL as “D-Bus Hell dot com” and was like… yup.

New comment by msarnoff in "Four Column ASCII (2017)"

msarnoff — Tue, 17 Feb 2026 08:48:54 +0000

On early bit-paired keyboards with parallel 7-bit outputs, possibly going back to mechanical teletypes, I think holding Control literally tied the upper two bits to zero. (citation needed)

Also explains why there is no difference between Ctrl-x and Ctrl-Shift-x.

New comment by msarnoff in "Unseen Footage of Atari Battlezone Arcade Cabinet Production"

msarnoff — Sat, 07 Feb 2026 23:27:14 +0000

Retro Game Mechanics Explained has a video about how the Asteroids vector generator worked and was coded for:

https://youtu.be/smStEPSRKBs?si=k_0u3NKCxCqZBc6w

Battlezone and later 3D games used different circuitry that generated vectors with analog circuitry and used a “math box” coprocessor based on Am2901 bit slice ALUs to help with the 3D math.

New comment by msarnoff in "Going for Gold: The Story of the Golden Lego RCX and NXT"

msarnoff — Wed, 14 Jan 2026 00:19:34 +0000

The ancestor of the RCX was the "programmable brick" project out of the MIT Media Lab in the mid-1990s

http://archive.pbrick.info/The%20MIT%20Programmable%20Brick%...

https://web.archive.org/web/20011212030110/http://fredm.www....

Growing up in New England at the time, I was very lucky that they ran a pilot project at my elementary school. We programmed our "sketches" (though we didn't use this term) in LogoWriter on Mac LC IIs and flashed them using a weird dongle that connected to the brick via RJ11 cable.

I owe a lot to my teachers and Fred Martin's group. I don't think I'd be a developer today without that experience.

New comment by msarnoff in "You can't fool the optimizer"

msarnoff — Wed, 03 Dec 2025 18:50:25 +0000

I was very surprised that GCC could optimize NEON SIMD intrinsics. After spending hours trying to optimize my vector code, trying to get the spacing between register dependencies right to reduce stalls, breaking long reduction operations into intermediate results, messing with LLVM-MCA, etc., I realized that I just couldn’t beat the compiler. It was doing its best to allocate registers and reorder instructions to keep the pipeline filled.

I don’t think it always did the best job and saw a bunch of register spills I thought were unnecessary, but I couldn’t justify the time and effort to do it in assembly…

New comment by msarnoff in "A vector graphics workstation from the 70s"

msarnoff — Mon, 01 Dec 2025 18:42:09 +0000

Storage tubes are amazing. I once had a Tektronix 464 scope. Unlike the ubiquitous 465, the 464 was an analog storage oscilloscope! The persistence of the storage tube let you capture pulses, visualize signal jitter, etc. And there was a very satisfying erase button that cleared the tube with the characteristic green flash.

You could also just mess with the horizontal/vertical position knobs and use it as a very expensive Etch-a-Sketch.

New comment by msarnoff in "Fran Sans – font inspired by San Francisco light rail displays"

msarnoff — Sun, 23 Nov 2025 22:17:18 +0000

When I was last at Penn Station in the 2010s their departure board was a mosaic LCD like the article, not a split-flap display:

https://upload.wikimedia.org/wikipedia/commons/b/bd/Penn_Sta...

I do miss the split flap displays at the Boston and Providence Amtrak stations though…

New comment by msarnoff in "Fran Sans – font inspired by San Francisco light rail displays"

msarnoff — Sun, 23 Nov 2025 21:28:10 +0000

I have seen these throughout the US and Europe and been fascinated by them. Penn Station has (had? been a while) a big one with more segments per character. I’ve been trying forever to find the name of this particular style of segmented displays and get more info on them. The closest I could find is “mosaic display.”

Love this article!

Signed, someone who has an obsession with segmented displays

New comment by msarnoff in "Runit Linux: Complete Guide to Unix Init Scheme with Service Supervision"

msarnoff — Mon, 17 Nov 2025 08:48:51 +0000

I've done small embedded Linux systems and it makes me so happy that there is a (mostly) compatible implementation built into busybox. svlogd's rotation and size capping makes it great when using limited-lifespan nonvolatile storage like eMMC.

New comment by msarnoff in "Show HN: I built an 8-bit CPU simulator in Python from scratch"

msarnoff — Fri, 24 Oct 2025 14:17:55 +0000

Instruction set looks very similar to the AVR, which is one of my favorites. Very cool!

New comment by msarnoff in "Electromechanical Calculating Machines from the 1960's"

msarnoff — Sun, 28 Sep 2025 15:06:26 +0000

I acquired a nonfunctional Diehl VSR a while back, naïvely thinking I could bring it back to life.

Oh my goodness, I took the cover off and what I saw was jaw-dropping. Thousands, possibly tens of thousands, of the most densely packed metal levers and cams and gears one could ever imagine. Nearly all of which would have needed cleaning and lubrication. Getting this thing fully working could have taken a year or more, especially with no repair manuals, and all available information in German.

The respect I have for the designers of these machines, and the servicepeople who repaired them, is immeasurable.

They are also electrical death traps. Lots of exposed switch contacts carrying mains voltage.

New comment by msarnoff in "Unified Line and Paragraph Detection by Graph Convolutional Networks (2022)"

msarnoff — Mon, 22 Sep 2025 08:17:43 +0000

I was there when we added it to Preview ;) I think Nils wrote the code to hook it up, because he also worked on the loupe and how it would automatically lock onto the bounding box of a line.

New comment by msarnoff in "Ultrathin business card runs a fluid simulation"

msarnoff — Fri, 08 Aug 2025 17:42:59 +0000

Surprise no one's mentioned yet that the firmware is written in Rust. As someone who's struggled with getting started with embedded Rust (the landscape seems to be changing quite a lot?) it looks like a good example.

Also it's a bit startling to see floating-point code used so freely. Shows how rapidly the capabilities of MCUs have developed. 15 years ago, doing floating point on a microcontroller would be unspeakable /s

New comment by msarnoff in "CoCo1 composite video"

msarnoff — Sat, 19 Jul 2025 01:04:52 +0000

Did this recently for my CoCo 2. Used a mashup of several composite mods floating around (including this one) and built it on a piece of stripboard that fit in the same footprint as the RF modulator. Sourcing the MC1372 was tricky, but NTE makes a replacement, NTE855. I used a 3.5mm TRS jack for the audio/video output so I didn’t have to drill a second hole in the case, and then all you need is a cheap 3.5mm stereo to RCA cable.

Wish I had a schematic but I kinda just wired it freehand.

New comment by msarnoff in "Congratulations on creating the one billionth repository on GitHub"

msarnoff — Thu, 12 Jun 2025 02:34:05 +0000

#SnakesOnARadar

New comment by msarnoff in "Hacking Pinball High Scores"

msarnoff — Sun, 01 Jun 2025 16:59:28 +0000

Assuming you have physical access to the inside of the machine…

Most all machines from the 80s and 90s (Williams/Bally/Gottlieb) store their high scores and adjustments in an SRAM like a 5101 with a battery backup. They are stored in binary-coded decimal and protected by a checksum.

If you could tap into the bus (possibly while the CPU is halted or by removing it) you could modify its contents.

A common aftermarket mod is to remove the backup battery (they like to corrode) and replace the CMOS RAM with a nonvolatile FeRAM. In that case, just pop it into a programmer like a TL866 and program a new image with your desired high scores.

I’ve considered doing this… I wish my 1.2 billion on my Getaway hadn’t been wiped out…

New comment by msarnoff in "Sleep apnea pill shows striking success in large clinical trial"

msarnoff — Mon, 26 May 2025 16:27:06 +0000

This comment needs to be higher. Atomoxetine is also known as Strattera and is prescribed for ADHD.

I tried it for less than a week and had to stop because there were VERY painful side effects _down there_.

I’m also a CPAP user and I’d 100% keep using it rather than go back on atomoxetine.

New comment by msarnoff in "About Asteroids, Atari's biggest arcade hit"

msarnoff — Mon, 19 May 2025 23:09:21 +0000

My favorite part of Jed's article:

"Part way through the run of Asteroids, we used up the world's supply of 7497s [binary rate multiplier chips] and Texas Instruments (the only manufacturer of 7497s) did not have them on their schedule to make more for several months"

New comment by msarnoff in "Sierpiński Triangle? In My Bitwise and?"

msarnoff — Sun, 11 May 2025 01:18:25 +0000

Munching squares!

New comment by msarnoff in "How MOS 6502 Illegal Opcodes Work (2008)"

msarnoff — Wed, 23 Apr 2025 14:38:02 +0000

Michael’s blog is one of my favorites. His “Ultimate Guide” talks are great and I rewatch them at least once a year.

Ultimate Guide to the C64: https://youtu.be/ZsRRCnque2E?si=v4qQ9mCx3MafEwAq

Ultimate Guide to the Game Boy: https://youtu.be/HyzD8pNlpwI?si=gn-F8yuRPJKoXmC7

Ultimate Guide to the Apollo Guidance Computer: https://youtu.be/xx7Lfh5SKUQ?si=3qbvMohcGo6mBLrJ