when I do not use FP routines... are those ZP locations free?

[Marius]

I need some ZP locations...

 

I don't use the FP routines, and Mapping the Atari tells me it is safe to use $D4 to FF then. I'm a bit 'scared' ... but please tell me mapping is right.

 

I also don't use BASIC. Can I also use D2 and D3 then?

 

I'm asking this, because I thought that everything from CB and up was free to use. So if it is not... I have to rewrite a few things.

 

Thanks

M.

[DanBoris]

I need some ZP locations...

 

I don't use the FP routines, and Mapping the Atari tells me it is safe to use $D4 to FF then. I'm a bit 'scared' ... but please tell me mapping is right.

 

I also don't use BASIC. Can I also use D2 and D3 then?

 

I'm asking this, because I thought that everything from CB and up was free to use. So if it is not... I have to rewrite a few things.

 

Thanks

M.

 

If you are not using Basic you can safely use $80-$D3, and if you aren't using FP then $D4-$FF should also be safe.

 

Dan

[Creature XL]

I need some ZP locations...

 

I don't use the FP routines, and Mapping the Atari tells me it is safe to use $D4 to FF then. I'm a bit 'scared' ... but please tell me mapping is right.

 

I also don't use BASIC. Can I also use D2 and D3 then?

 

I'm asking this, because I thought that everything from CB and up was free to use. So if it is not... I have to rewrite a few things.

 

Thanks

M.

 

If you are not using Basic you can safely use $80-$D3, and if you aren't using FP then $D4-$FF should also be safe.

 

Dan

If you do not believe him, I can confirm that as I use the locations from $80 upwards since years. As any assembler on A8 does

If you go a step further and do not even use teh Os you can use a lot more (maybe all?) locations.

[+Stephen]

Can anybody confirm that $D4 to $FF are free when using Turbo BASIC XL (when not using FP routines)?

[snicklin]

... if you're using CC65 (which I think not) then you can have problems with some of the ZP being used (as I found).

[Shawn Jefferson]

... if you're using CC65 (which I think not) then you can have problems with some of the ZP being used (as I found).

 

You should be declaring your variables as .zeropage, and then the compiler will allocate them into zeropage for you... no need to guess what's being used and where. I assume from your statement that you aren't doing this? (Well, to each his own, but there is an easier way to manage zeropage variables-really you shouldn't care (or even have to know) what zeropage address is actually being used by a CC65 variable.)

[snicklin]

... if you're using CC65 (which I think not) then you can have problems with some of the ZP being used (as I found).

 

You should be declaring your variables as .zeropage, and then the compiler will allocate them into zeropage for you... no need to guess what's being used and where. I assume from your statement that you aren't doing this? (Well, to each his own, but there is an easier way to manage zeropage variables-really you shouldn't care (or even have to know) what zeropage address is actually being used by a CC65 variable.)

 

Hi Shawn,

Thanks for your suggestion here. I wasn't actually using variables as such, I was POKE'ing directly to some locations and using these as "virtual variables". I've stopped doing this now, so it isn't a problem any longer.

 

Thanks, Steve