Search found 80 matches
- Sun Dec 20, 2020 4:37 pm
- Forum: Programming
- Topic: Interrupts - wedged code
- Replies: 11
- Views: 2878
Re: Interrupts - wedged code
The PRG is extremely vague in that regard. You'd better take a sharp look into the datasheet of the 6522 for this. Thanks Mike. I did have a look through the 6522 datasheet a couple of weeks ago, and it went over my head. Now that I've done a bit more reading it might make more sense. The Interrupt...
- Sun Dec 20, 2020 4:05 pm
- Forum: Programming
- Topic: Interrupts - wedged code
- Replies: 11
- Views: 2878
Re: Interrupts - wedged code
It never ceases to amaze me just how much is going on with such a 'simple computer'. I can see how IGONE and the other vectors nearby would come in handy for creating wAx. I'm right now reading the PRG chapter on VIA chips, but can't find anything about how to access them, or how they signal an inte...
- Sun Dec 20, 2020 12:10 pm
- Forum: Programming
- Topic: Interrupts - wedged code
- Replies: 11
- Views: 2878
Interrupts - wedged code
Hello. I've been having a mess with interrupts, and have managed to wedge my code in by 'poking' to address $0314-5. This is letting me create at least some semblance of 'multi-tasking'. Please can someone tell me if there any other methods of handling interrupts / event-driven stuff, or is that our...
- Sun Dec 20, 2020 8:40 am
- Forum: Programming
- Topic: Screen values vs PETSCII
- Replies: 11
- Views: 912
Re: Screen values vs PETSCII
From screenvalue to PETSCII input in X Y = X AND 63 IF (X AND 32) = 0 THEN Y = Y OR 64 IF (X AND 64) THEN Y = Y OR 128 result in Y (if X>127 then char is reverse) From PETSCII to screenvalue input in X IF (X AND 96) = 0 THEN REM it is a control code X = X AND 191 IF X > 127 THEN X = X AND 127 : X =...
- Thu Dec 17, 2020 10:18 am
- Forum: Programming
- Topic: Screen values vs PETSCII
- Replies: 11
- Views: 912
- Thu Dec 17, 2020 10:17 am
- Forum: Programming
- Topic: Screen values vs PETSCII
- Replies: 11
- Views: 912
Re: Screen values vs PETSCII
Ah... In reading the thread about memory location 36869 below, I decided to check out the reference to Compute's Programming the Vic... https://commodore.bombjack.org/vic-20/books-vic.htm pp585 in Appendix J lists 'screen codes', which is exactly what I was after. I can't believe I answered my own q...
- Thu Dec 17, 2020 10:10 am
- Forum: Programming
- Topic: Screen values vs PETSCII
- Replies: 11
- Views: 912
Screen values vs PETSCII
Hello folks. POKE 4096,1 (expanded VIC20) puts the character 'a' in the top left corner. POKE 4096,2 displays a b, and so on I was expecting PETSCII codes ( a= $41, b= $42 etc), but nope! Are the numbers a reference to the character 'map' in character ROM perhaps? What I found, with chars unshifted:...
- Fri Nov 06, 2020 11:45 am
- Forum: Other Systems
- Topic: Exactly how NOT to make a multicart for the C64
- Replies: 113
- Views: 8414
Re: Exactly how NOT to make a multicart for the C64
Sorry to resurrect this thread, but I've only just discovered it and wanted to congratulate all involved. It reminds me of a conversation I once overhead about the Duckworth-Lewis Method for determining who wins the cricket when it starts raining: ( https://en.wikipedia.org/wiki/Duckworth%E2%80%93Le...
- Fri Nov 06, 2020 11:35 am
- Forum: Other Systems
- Topic: Raspberry Pi 400 - Computer in a keyboard!
- Replies: 25
- Views: 9132
Raspberry Pi 400 - Computer in a keyboard!
Wow! We all thought that Clive Sinclair was insane, but he got it right... just 40 years too soon... It's fascinating that computer designers and manufacturers have gone pretty much full circle to end up at the place that we never left! IMG_20201106_173059939.jpg https://www.raspberrypi.org/products...
- Thu Nov 05, 2020 2:49 pm
- Forum: Programming
- Topic: ML Optimization discussion (split from: ROM calls and other tricks)
- Replies: 21
- Views: 1450
Re: ML Optimization discussion (split from: ROM calls and other tricks)
I'd presume quite a lot of fellow coders try to optimize their code for size or speed ... and never finish it. I think that, for me at least, this is as more about learning, about process and about engineering and optimizing code to the nth degree. I've got a big ol CRT monitor, real 1541, crappy o...
- Sun Oct 25, 2020 11:05 am
- Forum: Buy, Sell, and Trade
- Topic: SOLD: Final Expansion 3 Rev 11 [3rd Batch]
- Replies: 23
- Views: 15301
Re: Pre-Orders: Final Expansion 3 Rev 11 [3rd Batch]
Done, thanks.
- Sun Oct 25, 2020 4:01 am
- Forum: Buy, Sell, and Trade
- Topic: SOLD: Final Expansion 3 Rev 11 [3rd Batch]
- Replies: 23
- Views: 15301
Re: Pre-Orders: Final Expansion 3 Rev 11 [3rd Batch]
Hello Heather.
Please can I get a kit and case.
I'm happy soldering, but my sausage-fingers are no good at surface mount, so would appreciate you doing those bits for me.
- Sun Oct 25, 2020 3:45 am
- Forum: General Topics
- Topic: The Vic-20 launching Oct 2020
- Replies: 78
- Views: 5285
- Sat Oct 24, 2020 12:45 pm
- Forum: Programming
- Topic: Designing / Engineering a Biggish M/L Program
- Replies: 4
- Views: 509
Re: Designing / Engineering a Biggish M/L Program
Yeah, I tried that.
Probably explains all these grey hairs!
Time to get out the notebook and pen.
- Sat Oct 24, 2020 12:41 pm
- Forum: Programming
- Topic: Rewriting Kernal Routines
- Replies: 5
- Views: 434
Re: Rewriting Kernal Routines
Write your own chrout replacement from scratch with only the features you really need. You know what you want to achieve, the code has to simple reflect that. I've had a good poke around the internal organs of CHROUT and concluded exactly what you said: better just to write my own from scratch. I'v...