A software thing I built: GPS on a 25MHz 486-SX

45 pointsposted 8 hours ago
by JPLeRouzic
(forum.vcfed.org)

16 Comments

AshamedCaptain

36 minutes ago

I once worked on a handheld garmin gps that used a 386 ... not sure if it ever became a product, though. It definitely had moving map... 1MB of it.

SillyUsername

6 hours ago

I built one, tracking fleet vehicles with a custom box, using tiled maps, on behalf of Vodafone, back in 2002. I still remember I wrote a basic trans-mercator library too!

Of course Mercator projection may go out of fashion soon https://www.independent.co.uk/news/world/africa/world-map-eq... :)

Hope I'm called back to update the library ;)

philipallstar

3 hours ago

Probably not if navigation is involved:

> This is why most online mapping platforms like Google Maps or Apple Maps rely on a variation of the Mercator projection to provide directions. Using the Equal Earth projection for navigation would not be as effective as the Mercator projection.

> What the UN did was endorse the broader message that Equal Earth is a fairer projection that more equitably displays the true size of the Earth’s land

You are right about this though - it's a moral fashion. Who cares about land size on a map unless you've got the priorities and advancement of a prehistoric king? People with plenty of spare time who constantly talk in an echo chamber[0], that's who.

[0] https://un.org/en

guenthert

6 hours ago

"real-time GPS-driven moving map display"

Not the IMHO more interesting analog tech which lifts signals out of thermal noise.

JPLeRouzic

2 hours ago

That looks interesting, what technology "lifts signals out of thermal noise"?

peaseagee

36 minutes ago

Spread spectrum, it's pretty magical.

y04nn

an hour ago

DSSS, direct sequence spread spectrum, used for encoding GPS signal

tomaskafka

2 hours ago

A bit related - I tried if I can push Fable to write a Garmin map renderer that would be comparably fast (or faster) on Fenix 8 than the one they claim is possible on Fenix 9 only. I think I got very close, rendering detailed topographical vector map at over 15 fps on QEMU simulated single core simple CPU comparable to actual Fenix 8.

https://www.reddit.com/r/Garmin/comments/1vzaz4w/we_live_in_...

ErroneousBosh

6 hours ago

One of the things I discovered a while back is that even fairly crude trig approximations don't put that much error into your position, over a small enough distance.

To calculate things like straight-line range from where you are now to where you need to put a unit for an emergency, you're probably not working over an area of more than a couple of hundred kilometres radius and the error will be within a few dozen metres. And once you get within about half a k, you're driving towards the column of smoke anyway ;-)

contingencies

2 hours ago

In Y2K I built a Linux on PC104 solution with GPS, bonded dual-channel mobile 9600 baud data links, and a (slow) image feed. It was kind of special to see the data coming over the mobile network in those days: this was before mobile data using basic PSTN modem tech! Very lossy and slow, as the algorithms did not account for mobile voice compression.

JPLeRouzic

8 hours ago

The author says:

"It used Voronoi Cells and reduced most math to 8- and 16-bit integer calculations with one or two single-precision floating-point calculations."

I wonder if it can be used to speed up LLM inference.

Neywiny

3 hours ago

That's what quantization and stuff is, basically. So yes. Been done for years on all neural net types not just LLMs.

4RealFreedom

34 minutes ago

Quantization compresses the model’s parameters and you lose precision in the process. My understanding from the article was that precision wasn't lost - 'It actually had higher resolution than Extended-precision floating point math!'. The point of quantization is to make the model smaller to fit into available ram. I think the OP is referring to computation which is a different beast.

JPLeRouzic

2 hours ago

Please can you provide some links to intro level articles?