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Coprolite9000

Tiny BBC BASIC raytracer

Arx

@bbcmicrobot @coprolite9000 Ray tracing on an 8-bit computer, released 42 years ago, with a script short enough to fit in a Toot!

Coprolite9000

@arx @bbcmicrobot
It would take literally *hours* to run on original hardware - made implausibly faster by modern tech!

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@coprolite9000 @arx @bbcmicrobot How long do you think it would take on an Electron, and do you want me to try it and find out?

Coprolite9000

@coregaze @arx @bbcmicrobot
'A while', I imagine?

(If you've got access to original hardware, Owlet's got an audio export thingy which might be handy, saving a bit of typing. I'd love to see a photo of the poor Electron doing its stuff - I *think* the program will work unmodified?)

bbcmic.ro/tape/index.html?DATA

bbcmic.roBBC Micro Bot - Data Cassette
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@bbcmicrobot @coprolite9000 @arx I'm guessing more like eight, given that it has so far done this much, and it's been going for an hour and twelve minutes.

Another photo of my Electron, showing that the raytracer has made it past the first row of chequerboard squares and is about a third of the way through the second.
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@bbcmicrobot @coprolite9000 @arx Two hours, and it is apparent that the Electron's aspect ratio is slightly taller than the BBC's. I guess they don't want to keep the CPU halted longer than 40 µs if they can avoid it...

Maybe a quarter of the raytraced scene. The sphere is noticeably taller than it ought to be.
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@bbcmicrobot @coprolite9000 @arx Four hours and we're maybe halfway, or not quite halfway.

Nearly to the top of the lower sphere. Little Electron is going for it!
Coprolite9000

@coregaze @bbcmicrobot @arx
* Cheers on the little Electron *

(I wonder if it'll speed up a bit when it gets to the sky? The simpler gradient-only stuff might help a bit...)

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@coprolite9000 @bbcmicrobot @arx It seems to be managing a little over a pixel per second, I think, so far...

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@coprolite9000 @bbcmicrobot @arx the sky does indeed seem to be a little faster! Quite a bit, actually- maybe two or three times the speed. Five hours in and we're definitely past halfway!

Coprolite9000

@coregaze @bbcmicrobot @arx
Electron has achieved liftoff and is now soaring through the skies.

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@coprolite9000 @bbcmicrobot @arx 🚀 it is not.

But it's real.

My other Electron has a 2021 WDC 65C02S in it, it feels like that would be somehow less genuine; this Synertek part came from (another) Electron.

I don't know why I like the Electron so much. It makes me happy.

mstdn.social/@coregaze/1095835

Mastodon 🐘⚳ rapid unscheduled assembly ⚳ (@coregaze@mstdn.social)Attached: 1 image 1: I have done a thing. See, a while back when I was going through a pretty hard time (still am, tbh) my friend @erikarn gave me this Acorn Electron. This is one of the two most formative computers of my youth- the other being the Amstrad CPC (which @erikarn gave me a couple of years ago, dangit Adrian stop it). The problem was, though, that when I plugged an ElkSD128 into it, it... got very weird and unhappy. Like, biblically so. So I did this- but first I did some other stuff.
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@donkeyblam @coprolite9000 @bbcmicrobot @arx

And that's a wrap!

It took about eight hours and 40 minutes.

The final output from the BBC BASIC raytracer, at long last. The 40 microsecond active line used by the Electron is apparent; horizontal retrace is every 64 microseconds in PAL, and the active period is usually about 52 microseconds; the BBC uses an active line period that's a hair under 50 microseconds, while the Electron was designed to use a Synertek 6502A which is out of spec if halted for more than 40 microseconds.
A picture of my retro battlestation, moodily lit by the Electron's video output.
Coprolite9000

@coregaze @donkeyblam @bbcmicrobot @arx
Good work, little Electron! I hope you’re having a nice long nap now.

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@coprolite9000 @donkeyblam @bbcmicrobot @arx I wonder if it would be faster if I used my Electron with the 65c02 and the Master version of BASIC...

Arx

@coregaze @coprolite9000 @donkeyblam @bbcmicrobot Some of the graphics routines were optimised for Master BASIC, iirc. And the 65c02’s extra instructions help improve code density, so less memory access fetching instructions… so yeah, I expect so. Provided Master BASIC is compatible with the Electron, ofc.

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@arx @coprolite9000 @donkeyblam @bbcmicrobot I've run the 65c02 BASIC on my Electron, so it definitely works; the Electron OS is closer to the Master's OS 1.2 than to the Beeb's 1.0, I think.

Hmmm, this could be a fun project.

The bootup screen of an Electron with an ElkSD attached and with its ROM replaced by one containing a version of Master BASIC with the text patched to read "65C02" so I can tell which I'm running.
Arx

@coregaze @coprolite9000 @donkeyblam @bbcmicrobot That’s an excellent screen you have there. What is it and how have you connected it to the Electron?

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@arx @coprolite9000 @donkeyblam @bbcmicrobot It's a Waveshare 15.6 inch multitouch display (I don't use that last bit). amazon.com/gp/product/B07QXKKH

It's connected to the Electron via a Hoglet RGBtoHDMI based on a Raspberry Pi Zero.

Arx

@coregaze @coprolite9000 @donkeyblam @bbcmicrobot Cool, thanks :-) I need to get my Beeb out again. A fren kindly replaced the power supply. I need to check the real life behaviour arising from a hacked VideoULA palette register.

*
Arx

@coregaze @coprolite9000 @donkeyblam @bbcmicrobot How about using the RPi not only to convert the Beeb’s (edit: Electron’s!) RGB output to HDMI but also connects to, say, the user port so that programs can get the RPi to convert the colours using a 24-bit logical palette? Like a 21st century version of Mike Cook’s Chameleon. Maybe even get it to work with 2x2 pixel blocks so that it can do anti-aliasing. Massive cheat, I know, but fun to try! 😺

Arx

@coregaze @coprolite9000 @donkeyblam @bbcmicrobot Demo of a similar product from 1982! Signal from the RGB port. Colour remapping controlled via the user port. That RPi could SO do similar. 😺 youtu.be/Q5C0UOkDwVo?si=dGT9B7

YouTubeClwyd Technics Colour Palette enhancer for the BBC MicroBy Rob Coleman
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@arx @coprolite9000 @donkeyblam @bbcmicrobot I mean, apart from the fact that the Electron doesn't have a user port...

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@arx @coprolite9000 @donkeyblam @bbcmicrobot

Okay so I _may_ have spent a couple of hours making a ROM with the newest version of Electron MOS plus the newest version of BASIC 4 I could find.

An Electron boot screen showing a BASIC prompt. Upon issuing the BASIC "REPORT" command, it prints the BASIC copyright message, which reads "(C)1984 Acorn". Definitely not an Electron ROM...
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@arx @coprolite9000 @donkeyblam @bbcmicrobot It's my Issue 2 Electron board that has the W65C02S fitted, so over to that...

An Issue 2 Acorn Electron mainboard with a mezzanine containing a WDC 65C02S and a Lattice GAL to clean up and buffer the clock waveform. It also has a 27C256 EPROM fitted in place of the mask rom.
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@arx @coprolite9000 @donkeyblam @bbcmicrobot It is, it turns out, substantially faster than before? It's been going for about 45 minutes and this is how far it's got.

The BASIC raytracer output, which has gotten approximately one sixth of the output rendered in substantially less time than before.
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@arx @coprolite9000 @donkeyblam @bbcmicrobot Two hours and we're more than a third of the way in. I wonder what, if anything, running the Master BASIC in an Electron will break...

the same raytraced scene as yesterday, but this time more than a third of the way through in just two hours.
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@arx @coprolite9000 @donkeyblam @bbcmicrobot Three hours and 22 minutes and I think it's actually getting faster.

The same raytraced scene as before, but this time about two thirds drawn.
Coprolite9000

@coregaze @bbcmicrobot @arx
Aww - excellent. (Also, really interesting to read about some of the peculiarities of the Electron's hardware!)

My first home computer was a heavily upgraded Atari ST - starting life as a family computer in ~1988 when I was a child, then eventually getting on to the internet in ~1997 when I was a teenager. It acquired a hard disk along the way, which I've imaged and is bootable in an emulator - but I really ought to get the real hardware working again...

Coprolite9000

@coregaze @bbcmicrobot @arx
Last trip out for the ST - back in 2007?

(PPP over a null modem connection to a Linux PC under the desk in this case...)

Atari ST on messy desk with Google home page in monochrome on a CRT monitor.
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