can't help you with dd usage, but I adjusted your topic to be less *loud*. Posting in all caps is considered as shouting and very rude in forums.
I hope you can forgive my blatant abuse of moderator power 😀

Ops, sorry for my screaming subject 😀 and thanks for the correction! 😉

so,took a quick look, the point Truth made in the referenced post Direct3D games in DosBox is that when you fill the free space of an image with zeros, the image file can then be compressed to a much smaller archive (zip, rar, ...).
So I'm not sure you want that, because then for using the image you'd need to uncompress it first.

if you're using Windows NT 5+ and on NTFS you can use its internal compression, by setting the compression attribute.

Dominus wrote:

so,took a quick look, the point Truth made in the referenced post Direct3D games in DosBox is that when you fill the free space of an image with zeros, the image file can then be compressed to a much smaller archive (zip, rar, ...).
So I'm not sure you want that, because then for using the image you'd need to uncompress it first.

That's right, i don't want to compress image, i need the image always uncompressed because of i want it just ready to be mounted from dosbox, but at the same time i want to reduce space from it, to save hd space (i want to install only ONE game on my win98 image at time, so each configured window 98 game, for example of 100MB iso, too, needs for my purpose its own img file, that is 2GB --> very pointless space for each game!)
A solution to do this could be reduce partition to busy hd space (example 150MB OS + 100MB GAME = 250MB) and/or only resize hd image in a compatible geometry for dosbox imgmount command...Is there a way to do this?

By all means, no one is forcing you to use a 2GB image. Look up the guides section on using disk images.