C6502 has an interconection with CIA 1

Started by Baggey, March 17, 2023, 18:53:20

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So how do i get CIA 1 to interact with C6502 to make the CURSOR FLASH! anyone 8) :o :-X
Running a PC that just Aint fast enough!? i7 Quad core 16GB ram 1TB SSD. DID Technology stop! Or have we been assimulated!

ZX Spectrum 48k, C64, ORIC Atmos 48K, Enterprise 128K, The SID chip. ZX NEXT!? Oh i have a MISTY! Looking at a TEENSY! Could be better than a NEXTY!


From memory... and it was a long time ago, I seem to recall that the cursor flashing on and off was handled by the interrupt system. The long address in bytes 788 and 789, I think. You could use SEI to set the interrupts to jump to the location in these two bytes - address = peek(788)*256 + peek (789) - and then use CLI to clear the interrupt flag once it was done, after reseting the default location perhaps.

However, I'm probably waffling here because this might have just been a way for the user to add their own code to be handled by the interrupt routine, and the stuff like cursor was done before any of your own stuff, as long as you could get it all done before you reached the end of the scan line on your display device (tv, monitor or whatever)... It's been such a long time, though, and I wasn't that clear on it, even as a teenager.

I appreciate this post has probably been as useful as a chocolate fireguard :)


You could ask one of the guys here:  Sleeping Giant

it's a Vic 20 site, but these are seriously techy guys on the platform, and I'm 99% certain interrupts worked the same way on both the Vic 20 and the C64.