Mark MoxonMar 13

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

Index of all deep dive articles - The Sentinel on the BBC Micro

Index of all deep dive articles about The Sentinel

Show threadThomas AdamMar 13
@markmoxon Wow -- Why didn't I know about the sooner? Thanks for sharing! I'll be reading this as well!
Show threadMark MoxonMar 13

@thomasadam 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!

Show threadThomas AdamMar 13

@markmoxon I shall, Thank you.

One of the curios for me, is I recall certain programs back in the day, somehow, scrambling the "*L" command -- whereby it would just throw a hissy-fit.

I presume his was done through some assembly instruction, but I was never sure how...

Any thoughts?

Thanks again for all your writing, I'm really enjoying it so far.

Show threadMark MoxonMar 13

@thomasadam 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!

Show threadThomas Adam

@markmoxon Gosh, thank you, Mark. It probably is -- although from memory it felt as though prohibiting "*LIST" was more of a deliberate action than not.

Either way, you've given me enough to consider. I shall look forward to reading your articles nonetheless!

Thanks again!

Mar 13 at 6:35pmWeb
Show threadMark MoxonMar 13

@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… 🤣