Writing / Reading VRAM - noob questions

I am having trouble copying 1024 binary nametable to WRAM. Unfortunately, I do not have a WRAM preview in the emulator and I do not know if it is working properly. From what I can see it is copying incorrectly.

Binary is 1024 bytes, but only 768 will be used - the end of the load is marked with the FF pointer (tile FF as the indicator of when the loop is to end).

CopyNT:

	LD HL,NameTable						; src
	LD DE,$C000						; dst

CopyNT_Loop:

	LD A,(HL)
	CP $FF
	JR Z,CopyNT_End
	LDI
;;;;	INC DE                           ;problem here....
	JR CopyNT_Loop

CopyNT_End:

NameTable:	incbin "demo.nam" 	; 1024 byte binary nametable map (

Does writing to WRAM in MSX require anything else? Because the function should work.

EDIT:....
Ehh.., everything is fine, I can't delete the post - I didn't notice the additional INC DE (used before when I copied nametable every other byte). Now everything is ok.

It is not completely clear what you are trying to do.
If want to copy ram to ram, it can be done more efficiently using LDIR, refer to z80 docs about its working.

[Edit]
As thegeps said. Your solution is not only slower but also buggy as an FFh in the data would be interpreted as delimiter

I have no idea how to run Debugger in OpenMSX ...

My first test demo on MSX:
https://dl.dropboxusercontent.com/s/cyompte6mj3j1xm/msxdemo.rom
(Cartridge 32KB, SCREEN 1 mode)

It may not be anything spectacular at the beginning, but I am satisfied with it. Maybe I will come back to MSX in a while and write a simple game.

@siudym Greetings! It looks colorful and well animated
You should definitely try to develop a game! I see potential
The force is strong with you

Niiiice!, if you're targetting a MSX1 machine you can give it a try to Meisei emulator. Good enough to start with and has useful tools like the ones you're looking for (great VRAM viewers and so on).

OpenMSX has no MSX1 VRAM viewers, only MSX2 bitmapped modes can be inspected...