Good point. And it is easy to understand, that's for sure. The biggest confusion is when codebases mix sign-magnitude and signed numbers... but who would do that?
Well, apart from Bell and Braben, obviously. π
@markmoxon.bsky.social
Writer, walker, software archaeologist. Back in the day: Editor of Acorn User, Editor of h2g2. I love analysing old code, and my aim is to create the best code disassemblies you have ever seen. Purveyor of Elite/Lander/Revs hacks. www.markmoxon.com
Good point. And it is easy to understand, that's for sure. The biggest confusion is when codebases mix sign-magnitude and signed numbers... but who would do that?
Well, apart from Bell and Braben, obviously. π
Oof, Elite's sign-magnitude numbers are a bit of an acquired taste - I'm not sure whether I'd perpetuate that particular design decision! Multi-byte signed numbers might be easier to handle if you're after a bigger model space, though both solutions do work, so I guess it's down to personal taste!
10.02.2026 14:07 β π 1 π 0 π¬ 1 π 0Well, that looks pretty great! Nice to see it all working live. π
10.02.2026 13:37 β π 1 π 0 π¬ 1 π 0Yeah, it might take a while... but there's a lot to say. π
31.01.2026 16:17 β π 0 π 0 π¬ 0 π 1The list of deep dives that I am working on
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 thesentinel.bbcelite.com
It's going to take a while! But it should be worth it...
#retrocomputing #retrogaming #c64 #8bit
The Sentinel in embroidery
You didn't know you needed this in your life, but you do.
Marine Beaufils is a French artist who creates beautiful embroideries of... The Sentinel (amongst others).
It's inspired and quite beautiful. Enjoy!
www.marine.st/en/pages/sen...
#bbcmicro #zxspectrum #c64 #retrogaming #retrocomputing
Glad you like it - that full view is quite something!
12.01.2026 12:01 β π 1 π 0 π¬ 0 π 0Oh yeah, I see what you mean. Interesting, I guess that must be a typo in the MAME comment, because the ARM5 definitely isnβt a thing.
Itβs nothing to do with the subject of your blog post, though, so Iβll shut up and go back to reading the good stuff. π«‘
Totally agree.
11.01.2026 21:02 β π 1 π 0 π¬ 0 π 0Great article! Youβre one of the few bloggers whose stuff I always read, no regrets.
One thing: βthe DECO 156 was apparently a custom encrypted ARM5 CPUβ.
I donβt think thereβs such a thing as an ARM5? Could it be ARM3, ARM6 or possibly ARM7, given the timeline?
en.wikipedia.org/wiki/List_of...
Take away the slow panning and the tiny POV and it isn't really the same game. The faster versions are OK, as the strategy of the game is still great, but I do feel they miss out on the magic of the original.
Sometimes faster gameplay and bigger POVs arenβt better - theyβre just different, I guess!
It would be a different game, I suspect! The genius of the original is in the claustophobia of the small POV and the feeling of being trapped.
You know those dreams where you're desperate to run away but your feet are stuck to the floor?
That's the original version of The Sentinel.
And hereβs the thread on Stardot about it. Itβs been around for a while now!
stardot.org.uk/forums/viewt...
Itβs already been done! Atomic Elite is a real thing. π
I donβt know a lot about the Atom so Iβm not sure if it needs an upgraded machine, but it definitely exists.
github.com/oss003/Elite
The modern remakes, though? I bet they could do it no problem!
11.01.2026 18:23 β π 0 π 0 π¬ 1 π 0Also, the game uses the equirectangular projection, and that wonβt change, so all youβd get would be more of the existing view squished into each screen, rather than the perspective shift in Minecraft.
Not sure Quake Pro real is a concept within the equirectangular world, outside of zoomingβ¦ π€
Ah, OK found it - in Minecraft, WTF!
Yes, I think it would be possible to squeeze more angles into a single screen view, but the Beeb just doesnβt have the resolution for this to look good, and it would require a fair amount of recoding.
So thatβs probably a technical βyesβonly!
Whatβs Quake Pro field of view?
11.01.2026 17:56 β π 0 π 0 π¬ 1 π 0I might do a proper one-to-one at some point, but this took ages - loads of individual screenshots, each one cropped from the b2 export and then stitched together (the starting screen image in this thread is an example of a b2 export).
I wrote an ImageMagick script, but still, it took forever!
Also, they donβt match mode 5 pixels anyway, as they are rectangular, so thatβs another mismatch!
Theyβre just a bit of fun, not exact matches - I probably should have been explicit in saying this, but things always get missed out in these tiny messages!
Thatβs because I exported these from the b2 emulator, which applies a horizontal correction that canβt be disabled (thatβs the aliasing youβre seeing).
I didnβt say these were one-to-one pixel screenshots directly from the BBC screen, as they arenβt. They just show the full landscape in one go.
All three of which were born on the BBC Micro. π
You have good taste!
Well put! This game is a work of art and so atmospheric.
Scary too. And eerie at times. Itβs so cleverβ¦
The initial screen in The Sentinel
And here's the game's opening screen, for reference.
10.01.2026 17:20 β π 7 π 0 π¬ 0 π 0To see the landscape images in their full glory (i.e. without social media trying to be helpful), here are links to the full images:
Plain landscape: thesentinel.bbcelite.com/images/panor...
Landscape with grid points: thesentinel.bbcelite.com/images/panor...
Zoom in to see the detail...
For those who don't know, The Sentinel is a classic game from 1986, written by Geoff Crammond and published by Firebird.
It was originally released on the BBC Micro, and was converted to lots of other home computers, including the Commodore 64, ZX Spectrum.
See thesentinel.bbcelite.com for more.
So the game screen shows shows 1/9.7 of the full height and 1/12.8 of the full width of the landscape.
The weird figures are because the screen is a different shape to the full view.
Also visible is the point carΓ©e equirectangular projection used in the game. This is taken straight from Revs.
The first level in The Sentinel
The first level in The Sentinel showing grid points for panning and the first screen in red
Have you ever wondered how big the full landscape is in The Sentinel?
It's 1856 pixels high and 2048 pixels wide.
Here's the first level. The initial 192x160 screen is in red. Panning jumps the view to different grid points.
It's a big old world!
#retrocomputing #retrogaming #bbcmicro #c64 #8bit
Yes, you can look up a surprisingly long way, though in the early levels things are relatively flat so all you see is screen after screen of sky. When you look down you can see your own tile, so thatβs a bit easier to fathom.
Iβve been making panorama shots, so I might make a post on this topic!
In mode 5 pixels, the full landscape view is 1856 pixels high and 2048 pixels wide.
The game screen shows shows 192 by 160 pixels, so that's 1/9.7 of the full height and 1/12.8 of the full width.
The weird figures are because the screen is a different shape to the full view.
There you go!
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