@markmoxon@universeodon.com

I'm releasing over 50 deep dives into The Sentinel, Geoff Crammond's epic #BBCMicro game. Batch #1 is now ready: 6 new articles about memory maps, program flow and interrupts, all at: https://thesentinel.bbcelite.com/deep_dives Batch #2 (maths, lots of!) coming soon. Enjoy! #retrocomputing #retrogaming #c64 #8bit

thesentinel.bbcelite.com

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Mark Moxon @markmoxon@universeodon.com

· 7mo ago

I'm (slowly!) releasing 50+ deep dives into The Sentinel, Geoff Crammond's epic #BBCMicro game. Batch #2 is now ready: 7 new articles about maths, geometry, trigonometry… and Revs. https://thesentinel.bbcelite.com/deep_dives Batch #3 (landscape) coming soon. Enjoy! #retrocomputing #retrogaming #c64 #8bit

thesentinel.bbcelite.com

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Mark Moxon @markmoxon@universeodon.com

· 7mo ago

Just released: 6 brand new deep dives into The Sentinel on the #BBCMicro and #C64

This is where it gets interesting!

Generating 10,000 3D landscapes; tile data and shapes; enemies and trees; secret codes

https://thesentinel.bbcelite.com/deep_dives#latest

Batch #4 coming soon

Enjoy!

#retrocomputing

universeodon.com

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

This is pretty amazing. Draw accurate landscapes from The Sentinel on a pen plotter? And animate them? I'm definitely in! https://newsletter.revdancatt.com/p/085-the-sentinel-adventures-in-animation I do my projects for a lot of reasons, but seeing what people do with them? Yeah, that's a big one. 😀 #bbcmicro #c64 #retrocomputing

newsletter.revdancatt.com

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Documenting The Sentinel is really growing my collection of disassemblies at https://www.bbcelite.com

Five projects: Elite, Aviator, Revs, Lander, The Sentinel

1,038,891 words of source code commentary

507,016 words of deep dives

All Shakespeare's plays? 835,997 words

Or as the Bard himself may have written, if he were into 6502 assembly:

LDA #&2B
STA temp
EOR #&FF
ORA temp
STA question

I think that works? 😀

#retrocomputing #bbcmicro #c64 #8bit

bbcelite.com

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

New release: deep dives #37 to #40 for The Sentinel, Geoff Crammond's epic #BBCMicro game

This batch (#8) is a small release, covering the title screens, energy icons and scanner

https://thesentinel.bbcelite.com/deep_dives

Batch #9 is still in the oven, coming soon

Enjoy!

#retrocomputing #c64 #8bit

universeodon.com

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Time for some more deep dives into The Sentinel, Geoff Crammond's epic #BBCMicro game!

Batch #6 is now ready: 3 new articles about screen buffers, panning, scrolling and dithering

https://thesentinel.bbcelite.com/deep_dives

Batch #7 (drawing the landscape) coming soon

Enjoy!

#retrocomputing #c64 #8bit

universeodon.com

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Time for my last batch of deep dives into The Sentinel, Geoff Crammond's epic #BBCMicro game.

This one's a mixed bunch of miscellaneous topics, from anti-cracker code to hidden snippets of original source code. Short and sweet!

https://thesentinel.bbcelite.com/deep_dives

Enjoy…

universeodon.com

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Left image: The Sentinel and four sentries, taken from the landscape preview in the classic game of the same name. Astonishingly, these are not sprites. They are fully rendered 3D objects, using the exact same code as the game.

Right image: a robot, drawn by the same routine.

Micro *and* macro excellence! Very impressive from the same routine.

#retrocomputing #c64 #bbcmicro

universeodon.com

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Mark Moxon @markmoxon@universeodon.com

· 8mo ago

I've started writing a series of deep dives into Geoff Crammond's epic #BBCMicro game The Sentinel. Here's the to-do list. I will post a link here whenever I add a new one to https://thesentinel.bbcelite.com/ It's going to take a while! But it should be worth it... #retrocomputing #retrogaming #c64 #8bit

thesentinel.bbcelite.com

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Mark Moxon @markmoxon@universeodon.com

· 7mo ago

I'm (slowly!) releasing 50+ deep dives into The Sentinel, Geoff Crammond's epic #BBCMicro game

Batch #4 is now ready: 5 new articles about 3D objects (defining, drawing, managing)

https://thesentinel.bbcelite.com/deep_dives

Batch #5 (drawing polygons) coming on Friday

Enjoy!

#retrocomputing #c64 #8bit

universeodon.com

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Brand new weekend reading: even more deep dives into The Sentinel, Geoff Crammond's #BBCMicro epic

Batch #5 covers the unique equirectangular projection system, drawing filled polygons, the screen mode and more

https://thesentinel.bbcelite.com/deep_dives

Batch #6 soon…

Enjoy!

#retrocomputing #c64 #8bit

universeodon.com

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Mark Moxon @markmoxon@universeodon.com

· 7mo ago

This is pretty cool. It's a visualisation of the internals of The Sentinel on the #BBCMicro. This is it generating the game landscape for the first level from 1024 pseudo-random numbers. Next week I'll be releasing a deep dive into exactly how this works. *** A big thanks to Simon Owen, whose excellent repository I forked and enhanced in order to build this visualisation. It's well worth a visit. https://github.com/simonowen/sentland/ #bbcmicro #retrocomputing #retrogaming #c64 #8bit

github.com

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

What links The Sentinel with "Every Breath You Take"?

Why, it’s the minor added 9th chord, of course!

And the fact that they’re both 1980s classics

Find out more in batch #10 of my deep dives:

https://thesentinel.bbcelite.com/deep_dives

Batch #11 (last one!) soon

Enjoy!

#retrocomputing #c64 #bbcmicro

thesentinel.bbcelite.com

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Replying to

@cobbpg It’s the built-in assembler in BBC BASIC, which was used to write Elite, Aviator, Revs and The Sentinel (on the BBC Micro) and Lander/Zarch (on the Archimedes). It is a genuinely excellent assembler!

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Replying to

@geoffl@mastodon.me.uk @cs99cjb@hachyderm.io @frontierastro@universeodon.com Ha! Exactly. It’s click-bait, 1984-style. 🤣

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Replying to

@Workshopshed@mastodon.scot @frontierastro@universeodon.com Mostly. 😀

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Replying to

@drj @moonovermarine I do, yes, I posted about this a few weeks ago. Wonderful work! But I don’t think I knew the Mastodon link, so thank you. 😀

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Replying to

@Er_mecanico Time to bust out the Speccy! That’s one amazing conversion by Mike Follin. 👍

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Replying to

@MouseByTheSea@mastodon.gamedev.place Absolutely! This is a hobby, after all. 😀

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Replying to

@MouseByTheSea@mastodon.gamedev.place Thank you! I’m glad you like it. At the moment it’s mainly concentrating on the BBC Micro version, but I’m planning to add the Commodore 64 version too, along with some articles about the differences in the code. I just need to find the time - it’s been a big project, but it’d be nice to broaden its appeal.

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Replying to

@massimolauria Well, it's not emacs or vim, but it is just a text editor. It's Textastic on my iPad with a custom 6502 syntax colouring. https://www.textasticapp.com/ It's very handy when coding and writing on the sofa. 🙂 On desktop I flip between VSCode and BBEdit, though I disable almost every modern feature, especially anything that tries to be helpful. I can't be doing with any of that auto-complete popup nonsense! The only feature that is absolutely essential to my work is regex search and replace. I like it old school (though not quite emacs or vim!).

textasticapp.com

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Replying to on mastodon.gamedev.place

@cobbpg@mastodon.gamedev.place Yeah, that’s what the Bitshifters found with their BBC Master conversion - they needed the extra memory in the Master vs the standard Beeb. Squeezing it into the Apple II’s 48K is amazing! And given that 1.5K represents 6.5% of the entire Sentinel codebase, logs were out of the question! Same with Elite: the original BBC versions had algorithmic multiplication, but the C64 and co-pro versions had enough room for the log lookup tables. Seeing how they coded for constraints is one of my favourite aspects of analysing old code. 😀

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Replying to

@cobbpg Sounds fast! But presumably this approach is a bit more memory hungry? The Sentinel on the BBC Micro doesn't have any spare room at all, so I guess it's lowest common denominator for the core maths routines, which are copied unchanged from Revs. But by Stunt Car Racer he'd dropped the 32K platforms, so logarithms ahoy! Nice. 😀

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Replying to on bsd.network

@thomasadam@bsd.network Lots of disc games switch to the tape filing system after loading from floppy, so they can reuse the memory that would otherwise be used by the disc filing system. That would mean any *LOAD commands would then try loading from tape, which would appear to break if you were expecting it to load something from disc - not sure if that’s what you mean? Glad you like the writing!

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Replying to

@thomasadam@bsd.network Well, to be fair, this is pretty niche stuff and my Mastodon posts are fairly quiet affairs these days, so it's not that surprising if it slips under the radar. 🙂 I hope you enjoy the project, it's another labour of love!

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Mark Moxon @markmoxon@universeodon.com

· 7mo ago

Replying to on mastodon.social

@marksemczyszyn@mastodon.social That’s definitely the plan - I’d like to add the C64 versions of both The Sentinel and Revs to my site, as I did with Elite, and add deep dives on their unique aspects. It’s a bit of a long-term plan as I’ve got to finish the BBC Micro site first, but I bought a lovely original C64 last year and I’d like to celebrate it with a bit more coverage in my projects. Such a great machine!

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Replying to

@cs99cjb@hachyderm.io @frontierastro@universeodon.com It is pretty awful, isn’t it! In some runs it almost seems good, but in others it just gets stuck in a rut following a ship it can’t catch up with, spamming its lasers into empty space while being picked off by random pirates. The extra code isn’t that big, so I guess the algorithm will turn out to be pretty simple. We’ll see!

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Replying to

@plumduff69@mastodonapp.uk @frontierastro@universeodon.com Sounds great! Unless this is how SkyNet gets started… 😱

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Replying to

@thomasadam Oh, you’re talking about *LIST? *L. Is short for *LOAD, not *LIST, so I didn’t get that from your post. 😀 *LIST just dumps a file’s contents straight to the screen, so if it isn’t a text file, it will cause all sorts of chaos. And if paging is set (by pressing CTRL-N, for example) then that will set it to pause at the end of each page, and if you don’t know that SHIFT is the key to press to keep going, it will appear that the machine has crashed. Lots of potential explanations! Love these machines… 🤣

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Replying to

@MouseByTheSea@mastodon.gamedev.place I can’t argue with that! His code is really something; he’s such a great coder.

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Mark Moxon @markmoxon@universeodon.com

· 6mo ago

Replying to on mastodon.gamedev.place

@ludd@mastodon.gamedev.place My pleasure! Thank you for the kind words. 😀

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Mark Moxon @markmoxon@universeodon.com

· 5mo ago

Replying to

@plumduff69 Thank you! That is very kind, I’m glad you like it. 😀 Good luck with the rest of your project - I hope it’s as enjoyable as I’ve found this one!

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