Weeknight 'Virtual' Dev session #2, Thursday 10th September 2020, 7pm - 10pm

[spanners]

Will try to make an appearance, might be late on though.

[Arcadian]

I would like to attend if you can send an invite.

I would like to attend if possible. Thank you.

I'd like to drop in, probably won't make the start but hopefully be there in time for Kieran's interruptions

Calendar invites sent with Zoom info.

Will try to make an appearance, might be late on though.

Cool, nice one David - you should have the login info already I think (sent it via email).


Attendee list in the top post updated. Over 30 people should be online tonight. Wow.

[jzcoder]

Sorry to bother, but have not received zoom invite via email yet.

[Arcadian]

Sorry to bother, but have not received zoom invite via email yet.

Ah, ok - I'll PM it in a minute ... just launching the event ...

[Arcadian]

Sorry to bother, but have not received zoom invite via email yet.

Ah, ok - I'll PM it in a minute ... just launching the event ...

Now PM'd...

[0xC0DE]

What a great session! Huge thanks to Dave, all presenters and participants.

I got to show my 8-bit shenanigans to not 1, .... not 2,.... but 3 Acorn legends from the 80s! Talk about dreams coming true!

[Snuggsy187]

I know ! Turned me into a bumbling wreck !
Needed about 6 hours to discuss BBC/Electron Snapper versions with Jonathan !

Good work by the way Kelvin, I though I was nuts when I started using multiple sprites for printing...... glad you're doing the same !

Had an epiphany regarding Pooyan at 12 o'clock last night. Will post an update if I can get it to work.....

[sa_scott]

Thanks for a great session. I enjoyed seeing some of the demos near the end.

Would love to attend the next one!

[kieranhj]

Nice to see everyone last night and thanks again to Arcadian for organising. I hope the Intro to Interrupts session was practical and useful. All the text and asm code can be found on GitHub: https://github.com/kieranhj/intro-to-interrupts.

In the spirit of improvement, please feel free to PM me with one thing that might have made the session better / clearer / more useful for you, so I can take this onboard for next time.

It seems like there's enough interest for a CRTC Register Masterclass in future, but I might have a few weeks off first!

[Kevin Edwards]

I'm looking forward to catching up with some of the presentations I missed. The ones I saw were very inspiring and it's great to see people still developing for the Atom, Beeb, Electron and Archimedes.

Kieran, your 'introduction to timer interrupts' was superb! I remember trying to work out this stuff BITD with only the AUG and 6522 datasheets to hand. Took me a while to get it all up and running.

I also learnt something new - it takes 2us for the 6522 timer values to get copied across from the latch. Something that is critical for emulation to be correct. I think there's a tiny typo in the readme:-
"It takes 2ms for the latch value to be loaded into the counter registers" - should be 2us?

That's the first time I've seen Visual Studio code used for a presentation - much better than PowerPoint!

All the best.

[tricky]

Flibble, I can't remember if I said add a CLI or SEI, it should have been an SEI!

[tricky]

...The ones I saw were very inspiring...

How inspiring?

[0xC0DE]

How inspiring?

Very

[0xC0DE]

In the spirit of improvement, please feel free to PM me with one thing that might have made the session better / clearer / more useful for you, so I can take this onboard for next time.

Can't think of a single thing. You were born to be a teacher.

[0xC0DE]

Good work by the way Kelvin, I though I was nuts when I started using multiple sprites for printing...... glad you're doing the same !

Great to see what you are doing as well, Neil. I believe using pre-shifted sprites is quite common, especially on machines with no hardware sprites and an odd screen layout (looking at you Acorn!)

[dudleysoft71]

Good work by the way Kelvin, I though I was nuts when I started using multiple sprites for printing...... glad you're doing the same !

Had an epiphany regarding Pooyan at 12 o'clock last night. Will post an update if I can get it to work.....

I didn't think about it at the time it was only later that I thought about it.

If you lay out in columns with 8 bytes at the top of each column, plus 8 more at the end of the sprite you can render the whole sprite at any y offset by offsetting the start of your sprite data. You can even use the start padding from the next frame as the end padding of the previous frame. It means rendering one column then going back up and rendering the next, but it reduces the amount of sprite data to get the same effect. If your screen is 256 pixels wide then it's fairly cheap to do.

[tricky]

It's quite a short step from their to only draw the bit you need and a small speed-up.

[flibble]

Many interesting talks last night, and a big thanks to Tricky for assisting in the debugging of code for far too long

[Snuggsy187]

Thanks Dudley/Tricky.

I did start off with something vaguely similar, but offsetting the screen address instead - a bit painful. I like this idea better tho !

I'll have a play around with that and see how it goes.
Cheers

[edit] Screen width is 224 pixels (&1C0), which is a bit annoying actually. I guess I could enlarge it to 256, but then there'd be some loss of usable off-screen memory ! I'll ponder that too, it'd be nice to have the low byte of the screen address the same for every character row in a column !

[tricky]

Thanks guys, I like helping, it makes me feel like I'm achieving something without actually having to do it

[markdryan]

Another really enoyable and interesting evening. Thanks to Dave for organising and to all the presenters for the great talks and demos. After all this time, I finally understand how interrupts work on the BBC micro and can be put to good use.

[thearttrooper]

Was the zoom session recorded? If yes, please share the link. I missed a content rich session.

[kieranhj]

I'm looking forward to catching up with some of the presentations I missed. The ones I saw were very inspiring and it's great to see people still developing for the Atom, Beeb, Electron and Archimedes.

Kieran, your 'introduction to timer interrupts' was superb! I remember trying to work out this stuff BITD with only the AUG and 6522 datasheets to hand. Took me a while to get it all up and running.

I also learnt something new - it takes 2us for the 6522 timer values to get copied across from the latch. Something that is critical for emulation to be correct. I think there's a tiny typo in the readme:-
"It takes 2ms for the latch value to be loaded into the counter registers" - should be 2us?

That's the first time I've seen Visual Studio code used for a presentation - much better than PowerPoint!

All the best.

Thanks for the kind words & feedback Kevin and everyone, I'm glad you found the session useful. And great spot for that pretty critical typo!! I've updated the readme.asm file in the GItHub repo - another good reason for not baking everything into a PowerPoint presentation. It's great to see the developer evenings really take off, I hope they inspire more people to start developing their own projects.

[Arcadian]

Part 2 of Kieran's Masterclass on BBC Micro Interrupts has now been added to the ABug website! Thanks Kieran!


Acorn Masterclass: An Introduction to Interrupts on the BBC Micro – Part 2

[Arcadian]

Tricky's "Mini" Masterclass from the 10th September session has finally been added to the ABug website.


Mini Masterclass: Using interrupts without an interrupt handler

Watch out for a couple of 'surprise' guest appearances towards the end!

[RobC]

Can't remember who it was but someone (possibly Mark?) asked about using the Norcroft C compiler with floating point on the Arm 2 co-pro and how this works when you can't load the FPE module. I recalled having done this but couldn't remember the details.

Having checked at lunchtime, the answer is that there's a version of FPE for the ARM Eval system - you load this in and it changes the prompt to show the floating point emulator has been loaded.

According to this, the FPE is on disc 3.