Last Cursor Location (Assembly)

[DusanStrakl]

Does anybody knows how where might the last cursor position on screen when the program was started be stored (Assembly or Basic)?

 

Thanks,

Dusan

 

[StephenHorn]

1 hour ago, DusanStrakl said:

I tried it before and it looked like it was not working, now I tried it again and it works but it puts positions in opposite registers, Y returns column and X returns row number. That confused me before. It does the same thing when setting the coordinates.

 

16 minutes ago, SlithyMatt said:

Sounds like a bug. You should report it on the ROM repo: https://github.com/commanderx16/x16-rom/issues

No bug, that's actually how that's supposed to work, apparently.

https://www.c64-wiki.com/wiki/PLOT_(KERNAL)

[SlithyMatt]

Have you tried the PLOT function in the Kernal ($FFF0)? If you set the carry bit, it should put the cursor position in the X and Y registers:

sec

jsr $FFF0

That's what the C64 kernal would do, but I haven't had a need to do it with the X16.

[DusanStrakl]

I tried it before and it looked like it was not working, now I tried it again and it works but it puts positions in opposite registers, Y returns column and X returns row number. That confused me before. It does the same thing when setting the coordinates.

[SlithyMatt]

56 minutes ago, DusanStrakl said:

I tried it before and it looked like it was not working, now I tried it again and it works but it puts positions in opposite registers, Y returns column and X returns row number. That confused me before. It does the same thing when setting the coordinates.

Sounds like a bug. You should report it on the ROM repo: https://github.com/commanderx16/x16-rom/issues

[SlithyMatt]

Hmm... seems something is amiss, because the Kernal reference that I usually use says the opposite: https://sta.c64.org/cbm64krnfunc.html

I wonder which way the C64 (or VIC-20) does it?

[DusanStrakl]

I was just looking into it and this document says opposite:

https://sta.c64.org/cbm64krnfunc.html

Also function SCREEN returns width in X and height in Y

I just posted it as bug and will see what dev will say.

Edited April 29, 2020 by DusanStrakl

[SlithyMatt]

This tutorial says they are supposed to be switched, too: http://retro64.altervista.org/blog/very-basic-basic-plotting-characters-screen-c64-and-vic-20/

I guess that means that my usual reference is not 100% correct. 

This OCR scan of an original CBM programming guide also says they should be switched, so it looks like there is no bug, for sure.

Edited April 29, 2020 by SlithyMatt

[Perifractic]

1 hour ago, DusanStrakl said:

I just posted it as bug and will see what dev will say.

This reminded me to add a bug report link to the GitHub (for now) in the Help & Support forum here. Thanks.

[Perifractic]

21 hours ago, StephenHorn said:

No bug, that's actually how that's supposed to work, apparently.

https://www.c64-wiki.com/wiki/PLOT_(KERNAL)

(This is a test reply to the "best answer")

[StephenHorn]

9 minutes ago, Perifractic said:

(This is a test reply to the "best answer")

And I pretty much got the push notification from that immediately, even though I'd left the site open and idle for some hours. So that seems to work well.

[Perifractic]

43 minutes ago, StephenHorn said:

And I pretty much got the push notification from that immediately, even though I'd left the site open and idle for some hours. So that seems to work well.

That's good. It also supports push on mobile.