How to change cursor position?

adric22 · Post by **adric22** » Tue Nov 13, 2012 2:13 pm

I'm having a heck of a time finding this with google. On the C64 there are two locations I can POKE for X,Y coordinates and then execute a SYS command and it will plant the cursor in a particular place for the next print statement. I can't seem to locate the equivalent on the VIC-20. Can somebody help?

rhurst · Post by **rhurst** » Tue Nov 13, 2012 5:00 pm

Not recalling if I used this myself, but in Programmer's Reference Guide of user callable kernal routines:

PLOT Read/set X,Y cursor position @ $FFF0 (65520)

I believe X = rows, Y = cols in this case, and zero based.

Boray · Post by **Boray** » Tue Nov 13, 2012 5:03 pm

Aren't those kernal calls just the same as on the c64?

Boray · Post by **Boray** » Tue Nov 13, 2012 5:05 pm

Maybe the "poke" locations of the A X Y registers before a SYS isn't?

adric22 · Post by **adric22** » Tue Nov 13, 2012 5:28 pm

Boray wrote:Maybe the "poke" locations of the A X Y registers before a SYS isn't?

You know what.. I bet you are right.

Kweepa · Post by **Kweepa** » Tue Nov 13, 2012 5:45 pm

I just checked the PRG for each machine, and the memory locations are the same for each.

POKE781,X:POKE782,Y:SYS65520

The only difference is that (X,Y) is (column,row) on the VIC (sensible) and (row,column) on the C64 (stupid). Of course that could be a typo.

adric22 · Post by **adric22** » Tue Nov 13, 2012 7:41 pm

Kweepa wrote:I just checked the PRG for each machine, and the memory locations are the same for each.

POKE781,X:POKE782,Y:SYS65520

The only difference is that (X,Y) is (column,row) on the VIC (sensible) and (row,column) on the C64 (stupid). Of course that could be a typo.

I bet it is a typo because the last time I used that on the C64, I noticed the X and Y were backwards from what was documented.

Pedro Lambrini · Post by **Pedro Lambrini** » Wed Nov 14, 2012 9:35 am

So, can I ask something?

If you put the above line between two print statements the program would print the first statement in the top left as normal and then the second line would print wherever X and Y are?

adric22 · Post by **adric22** » Wed Nov 14, 2012 11:13 am

If you put the above line between two print statements the program would print the first statement in the top left as normal and then the second line would print wherever X and Y are?

Correct. usually this is much faster than trying to have some kind of loop using cursor movements if you need a dynamic way to move things around on the screen.

Pedro Lambrini · Post by **Pedro Lambrini** » Wed Nov 14, 2012 11:57 am

^
Cool. Thank you.

I am incredibly bad at programming and have always put cursor key presses in my print statements as I knew of no other way. POKEing just has to run faster than that!

Boray · Post by **Boray** » Wed Nov 14, 2012 12:14 pm

Alternatively you could use the TAB() function combined with a home made function for the y pos:

Code: Select all

10 L$="{home}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}{down}"
20 PRINT LEFT$(L$,12)TAB(11)"HELLO"

Boray · Post by **Boray** » Wed Nov 14, 2012 12:19 pm

Or maybe this is smaller:

Code: Select all

10 L$="{home}":FORT=1TO22:L$=L$+"{down}":NEXT
20 PRINT LEFT$(L$,12)TAB(11)"HELLO"

Boray · Post by **Boray** » Thu Nov 15, 2012 8:09 am

Splitted the following discussion to a new thread:
"Garbage Collect (splitted)"
http://sleepingelephant.com/ipw-web/bul ... hp?p=67886

Post by **Jeff-20** » Thu Nov 15, 2012 12:25 pm

Maybe I am misunderstanding the question, but here's my simple solution:

Code: Select all

1 PRINT SPC(22*Y) SPC(X);

Works for me.

Boray · Post by **Boray** » Thu Nov 15, 2012 12:35 pm

Jeff-20 wrote:Maybe I am misunderstanding the question, but here's my simple solution:
Code: Select all
1 PRINT SPC(22*Y) SPC(X);
Works for me.

Oh, so it does! I thought SPC printed a real space. So it seems TAB and SPC is the same function then.