Post by @EdS@mathstodon.xyz

EdS

@EdS@mathstodon.xyz 4 hr. ago

RE: https://mathstodon.xyz/@ColinTheMathmo/117541365267314431

factoring - sounds good! we intersected this with #retrocomputing not so long ago.

Factorising to give prime factors [stardot]
https://stardot.org.uk/forums/viewtopic.php?t=25609

https://stardot.org.uk/forums/viewtopic.php?t=25609

Colin the Mathmo

@ColinTheMathmo@mathstodon.xyz 4 hr. ago

I'm giving a talk online at 13:00 Atlanta time, 18:00 UK time, about 4:45 from when I post this:

“Factoring Integers by Chasing Rabbits in Circles.”

https://www.gathering4gardner.org/news-2026-10-30/

I have no idea what hashtags I should use for this.

Anyway ... the title and abstract are on that page.

Less than 5 hours ... I should be planning what I'm going to say ...

#retrocomputing

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Colin the Mathmo

@ColinTheMathmo@mathstodon.xyz 3 hr. ago

@EdS That's an intriguing thread ... thank you.

I've done a lot of programming in BBC BASIC, including safety-critical applications, and I've done a lot of programming in assembler (and machine code), so all of that was very much in my wheel house.

These days I tend not to be involved with that side of things, but it's nice to see it all.

The talk I'm giving is explaining Pollard Rho and the ideas of the maths underneath. Very much a skim over the top, but some of it will feel familiar. I'm not going to focus on the implementation, or speed efficiencies. That would be another talk entirely.

Even so ... hope you can make it, and hope you find it interesting.

penguin42

@penguin42@mastodon.org.uk 3 hr. ago

@ColinTheMathmo @EdS What safety-critical BBC BASIC stuff did you do?

Colin the Mathmo

@ColinTheMathmo@mathstodon.xyz 2 hr. ago

@penguin42 I'm not sure I can talk about it too much, even though it was a long time ago. Suffice to say that I work with a company that produces VTMIS equipment. This is kit that people use to do the maritime equivalent of Air Traffic Control.

So we produce, supply, and install the kit, then train our customers on how to use it to monitor the traffic through their area of responsibility. Many years ago some of the software was written in ARM assembler, some was written in C, and some in BBC BASIC, as well as a smattering of other supporting script-like languages.

After a while the fact that we used RiscPCs was costing us contracts ... people insisted on hardware they'd heard of, and that they could buy from multiple manufacturers, so we were forced to move to standard "PC" hardware. The story of managing that transition is a long one.

CC: @EdS

penguin42

@penguin42@mastodon.org.uk 2 hr. ago

@ColinTheMathmo @EdS Fun; I think that's the first time I've heard of a RiscPC being used in commercial use; and I had worked for a place that used earlier Arc's and Beebs for doing interactive Museum displays and similar. (And used an Arc for patient records in my dad's pharmacy)

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