What is retained?

[Tursi]

It's not fixed. We have a few threads how, at least for XB, to reserve memory above the program. Normally we do that to load assembly code along with the XB.

[+InsaneMultitasker]

Well, whatever version of BASIC is required... you need to figure out what addresses to modify to reserve memory to store the data at or how to temporarily hide/un-hide the variable data.

If the start address of where variables is stored is fixed in ROM/GROM and can't be modified in RAM, then you may be out of luck.

Pointers and modifying address all depends what memory you are talking about.

 

In my example, the space available when you BREAK (FCTN-4) the program can be used, starting at 0xA000. Numeric variables are allocated at run time and do not grow so the remaining free space is a true reflection of what is available. In some of my programs, I rely upon this free space factor so that I can dedicate the lower 8K to assembly code while pushing temporary buffers and such into that upper 24K.

 

Other areas such as VDP stack are much more volatile. They are also harder to manipulate and do indeed require more attention to pointers and reserved spaces, as well as support from assembly or subprograms not found in standard XB.

[Opry99er]

You guys are masters!!

 

Ive been doing a little testing here on my end but have not been able to READ data into upper memory and PEEK it back in to the chained program.

 

It is likely a user error, so I will post my sample code tonight when I get home... See if you guys can point me in the right direction.

 

Thanks for the discussion, fellas. Fascinating!