Hacker News: billforsternz

New comment by billforsternz in "I designed a nibble-oriented CPU in Verilog to build a scientific calculator"

billforsternz — Sat, 16 May 2026 01:51:37 +0000

The Z80 does have a DAA (decimal adjust arithmetic) instruction to facilitate BCD arithmetic. I don't think I ever used it in my Z80 years and I'm not familiar with the details. Sadly I have much less experience with the 6502, I didn't even know it had a BCD mode.

New comment by billforsternz in "Chess puzzle I found in my dad's old book"

billforsternz — Thu, 14 May 2026 04:01:47 +0000

The wording is very unambiguous, it means something very specific in chess. In every legal chess position either White is checkmated or Black is checkmated or (by far the most common except in film and TV!) neither side is checkmated. So the wording is crystal clear, you should be able to freely place the White king on any of the unoccupied 59 squares and the position will be one of those in which White is checkmated.

A real shame, this totally ruined the puzzle for me as it seemed so unlikely that all five Black pieces would be mutually protected. I should have forced myself to ignore the faulty clause and try to solve without it. The bad clause is also completely unnecessary - one of those cases where deleting text (or code!) is an improvement with no downside!

New comment by billforsternz in "Why TUIs are back"

billforsternz — Mon, 04 May 2026 05:05:24 +0000

I is tab ('\x09' or '\t') and J is new line ('\x0a' or '\n'). These Ctrl combinations follow a predictable linear mapping to the control character section of the ASCII table. Basically Ctrl subtracts 0x40, so I is 0x49, Ctrl I is 0x09.

New comment by billforsternz in "Ti-84 Evo"

billforsternz — Fri, 01 May 2026 22:26:24 +0000

Thanks for clarifying. I think this is an ARM and a break from a history of Z80 and Z80 adjacent CPUs. I do get the impression TI have done a good (financial) job milking these products whilst under investing in real product innovation.

New comment by billforsternz in "Ti-84 Evo"

billforsternz — Fri, 01 May 2026 21:48:45 +0000

Surprisingly high or surprisingly low?

New comment by billforsternz in "Consequences of passing too few register parameters to a C function"

billforsternz — Thu, 30 Apr 2026 03:46:11 +0000

Yes. And in the second one he has return c; when he meant return b;

Homer nods.

New comment by billforsternz in "The Secret Life of NaN (2018)"

billforsternz — Wed, 29 Apr 2026 21:42:10 +0000

We're both seeing rudeness. We both dislike rudeness. I think it's rude to rain on someone's parade. You think it's rude to assume someone hadn't thought through their comment (I basically agree) and to address the person rather than the points (I also basically agree).

You might note my original comment included softening elements ("perhaps", "not saying you're wrong"). In general if you look at all my comments you'll see I'm not a rude person, I'm pretty agreeable in general.

I was (trying to) make a meta point rather than a point about the specific technical issue. I agree (again!) that the last word has not been said on this issue or on any other issue where tradeoffs need to be weighed.

I read Walter's comment and thought "Wow, that's a surprising, clever and innovative idea, I'm impressed". And I just didn't enjoy someone bluntly saying, in effect. "No you're wrong, you shouldn't do it like that". It's as simple as that really. I know blunt exchanges of views are normal for programmers and engineers, I don't have to like it every time.

Finally, I know Walter Bright is no shrinking violet and he definitely doesn't need me to defend him!

New comment by billforsternz in "The Secret Life of NaN (2018)"

billforsternz — Wed, 29 Apr 2026 02:29:12 +0000

I wasn't really appealing to authority. I was just suspecting a familiar pattern that I always find a little distasteful. Person A describes a brilliant idea they're obviously proud of. Person B casually dismisses it and just claims without evidence that the obvious way of doing it is better. I find that pattern to be not only rude, but to suck some of the joy out of life. The fact that person A on this occasion is widely acknowledged as a brilliant practitioner I thought added weight to me pushing back. But I'd be inclined to feel the same way if person A was an enthusiastic wide eyed student (say) with a fresh perspective.

New comment by billforsternz in "The Secret Life of NaN (2018)"

billforsternz — Tue, 28 Apr 2026 03:22:46 +0000

How long did you think about this before making this declaration? How long did Walter Bright think about this before making his decision when designing his language? Not saying you're wrong, just something to think about perhaps.

New comment by billforsternz in "Alberta startup sells no-tech tractors for half price"

billforsternz — Fri, 24 Apr 2026 02:22:09 +0000

Sir Edmund Hillary and his team drove early Massey-Fergussons to the South Pole in 1958 (much to the annoyance of Sir Vivian Fuchs who Hillary beat to the pole even though Hillary was supposed to be a support player only :). The tractors weren't really suited to the job but they were tough enough to make it anyway.

New comment by billforsternz in "XOR'ing a register with itself is the idiom for zeroing it out. Why not sub?"

billforsternz — Wed, 22 Apr 2026 19:41:59 +0000

Back in the early 1980s I leveled up my self taught Z80 assembly skills by reading a book that attempted to disassemble and explain the Sinclair Spectrum ROM.

I remember the very first ROM instruction was XOR A and this was already a revelation to me as I'd never considered doing anything other than LD A,0 to clear the accumulator.

New comment by billforsternz in "Show HN: A (marginally) useful x86-64 ELF executable in 301 bytes"

billforsternz — Thu, 09 Apr 2026 10:09:40 +0000

I would prefer avoiding the infinite loop and printing a message to help the user understand what went wrong. I'm sure you could do that with an extra 100 bytes or so. Just my opinion of course.

New comment by billforsternz in "How many products does Microsoft have named 'Copilot'?"

billforsternz — Sun, 05 Apr 2026 04:46:16 +0000

I remember Joel of Joel on Software publicly working through the process of creating a remote desktop for normals type product called Copilot back in the day. If I remember correctly he had to pay quite a pretty penny to acquire copilot.com.

I wonder if MS Copilot meant he made money on that investment?

New comment by billforsternz in "How many products does Microsoft have named 'Copilot'?"

billforsternz — Sun, 05 Apr 2026 04:42:57 +0000

We should probably be grateful Microsoft didn't name it .NET

New comment by billforsternz in "AirPods Max 2"

billforsternz — Tue, 17 Mar 2026 06:47:53 +0000

By convention if it was 13.600 they would present it as 13.600 not 13.6. If I remember correctly Everest was first surveyed as 29000 feet tall and they changed it arbitrarily to 29002 to avoid the apparent imprecision!

New comment by billforsternz in "AirPods Max 2"

billforsternz — Tue, 17 Mar 2026 04:05:55 +0000

386 grams, the extra 0.2 grams is not only irrelevant it's non existent because the process of converting from one measurement standard to another never increases the precision of the measurement.

Using 3 digits of precision also avoids being temped to use the rather niche ,2 convention when claiming to embrace a region as large as the rest of the world.

New comment by billforsternz in "“This is not the computer for you”"

billforsternz — Fri, 13 Mar 2026 20:16:43 +0000

C dev wasn't a problem with MSDOS and 640K either. With CP/M and 64K it was a challenge I think. Struggling to remember the details on that and too lazy to research it right now.

New comment by billforsternz in "Big data on the cheapest MacBook"

billforsternz — Fri, 13 Mar 2026 04:42:18 +0000

The almost regretful "I'm not Norwegian" clarification here is charming.

New comment by billforsternz in "Z80 Sans – a disassembler in a font (2024)"

billforsternz — Sun, 08 Mar 2026 23:39:29 +0000

I thought my Z80 project (https://github.com/billforsternz/retro-sargon) was close to the whimsical end of the practical to just for fun spectrum but this takes things to a whole new level, kudos.

New comment by billforsternz in "Put the zip code first"

billforsternz — Sun, 08 Mar 2026 00:16:21 +0000

It's very interesting how the "you know the city, the state, the country" mantra here is really "you know the city, the state and obviously the country is the USA no other possibilities are considered or worth considering"