Ofcourse, I tried to find this out on the web first before deciding to bother you lot with it.

(1) Exactly how much extra (MSX 2) RAM is preserved when booting with [CTRL] pressed?

(2) In BASIC, what's a reasonable begin/start address to CLEAR? How to tell what's the amount of bytes needed for your strings, arrays and program itself?

(3) How to tell if allocated memory ain't gonna overlap used memory or clash with running TSR's etc.?
Or is it refused or 'cut down' automatically when you CLEAR too much?

(1) I believe this depends on the MSX model. Not sure about this though. In any case, with CTRL you will get some extra BASIC memory, which is what it's all about I think

(2) This is a matter of bookkeeping - check your listing to see how much memory your variables and strings take up, then use that to CLEAR. The address to CLEAR from is then the BASIC top address minus the amount of bytes you calculated in the first place.

(3) I haven't got the slightest clue. I don't work with TSRs [MemMan?] and stuff, but I guess that if you use a proper memory manager like MemMan, your CLEAR will be automatically cut down [out of memory<beep!>].

There is this command on msx basic
Print fre(0)
on bluemsx on a msx2 profile without ctrl it gives 23432 bytes with control pressed it is 24990.

You can just do this and it will instantly tell you of the basic free memory.

Boot with the CTRL key pressed, you disable the diskrom, this is about 16k, IIRC
OR is it 1.6k?

SHIFT, CTRL only disables the 'second' drive

legacy: it's 1.6k . As msd said, SHIFT will increase the BASIC memory to 28815 bytes if I'm correct. At the expense of disabled drives, that is

Is it possible to use 128KB instead of 64KB RAM for a BASIC program + XBASIC + music player + sfx player ?

In basic (or xbasic) you cannot use more than 26-28Kbytes,
only ASM programs can use more ram.
Maybe you could use the extra ram as ramdisk, but the max size
of ram usable for programs stay 26-28Kbyte.

It is even possible to use, like, 4Megs in BASIC. Therefore your BASIC program should start on $C000, such that page 3 can be swapped with anything else [like a memory mapper!]. Disadvantages are huge: you'd have to do your own memory management in BASIC, DOS2 can not be supported at all and foremost: the size of your BASIC program ends up being 8-10kB.

According to MSX2 Technical Handbook, chapter 2:

Quote:

When developping a program on MSX2, we recommend you create it at addresses 8000H to DE3FH as if to install a 2DD-2 drive whose highest address of the user's area is the lowest. The work area of the disk can grow even larger, therefore, HIMEM of the application program should be checked to prevent disasters even in the worst situation.

This is true for DOS1, DOS2 will never take so much amount of system memory. Anyway, always check HIMEM (FC4AH) to know where the BASIC area ends.

As for (properly programmed) TSRs, these will cause the system to decrease available memory automatically, so you don't have to worry about them.

And if you want to use mapped RAM from BASIC, one option is to use NestorBASIC.

That was the ultimate alternative that I forgot to mention, thanks konamiman

Oh guys, great!!!

You are seriously saving over 9 months of work from going down the drain!

NestorBASIC sounds good.

One big disadvantage of helping me is:
I will be back with stupid questions shortly.

F.I., I have to clue about letting BASIC programs start on different addresses or swapping pages.

DemonSeed: rest easy, with NestorBASIC, you don't need to know that kind of stuff. I'll answer your e-mail on short notice though, so stay tuned