Hello. I guess this question is probably asked once a week, but I just could not find it in the last posts.
I started playing Metal Gear 2 on NLMSX in the last days, but I don't want to write it down that huge password. So, when I tried saving on the disk, a message appeared saying that it (disk) was not prepared.
What should I do? Please someone answer me. Thanks.

In order to save to disk, you need ... you guessed it, you need disk !
In fact, a disk image, 360 or 720K file.

You have to either prepare it using wrdsk or any other disk image creation utility,
or do the following trick:

1) make any empty file (right click->new->some file type) with .dsk extension
2) open it in NLMSX (F6)
3) in MSX-BASIC, type

call format

and answer the questions it asks.

Now you have a formatted disk image to be used for game saving.

The command call format is not yet implemented in NLMSX.

So, to create a new formatted DSK image, the best tool is Disk Manager, that you can find on the RuMSX site (another emulator ... with a working command call format).

You must click on File / New, then select the case Disk format /capacity and select the following option: 2 sides, 80 tracks, 9 sectors/track (720 Kbytes). You save this empty formatted disk by clicling on File / Save as ...

Erm.. so how it happens call format, then saving and loading worked for me in NLMSX ?

Do you have checked the size of the DSK file after pseudo-formatting in NLMSX ?
I've tried your method ... and the size of the DSK file was only 11 Kb !

While it works, the size of DSK file doesn't matter, am I right ?
Of course, I checked the size of file.

If you try to save a file of 12 Kb on a DSK image of 11 Kb, it won't work at all ...

[EDIT]

Well, it's very strange ... my first answer was only pure logic .... but then I had a doubt and I've tried to copy a file from disk image in drive B to this DSK image of 11Kb in drive A ... and it seems to work, the new size of the DSK image in drive A has changed to 23 Kb ....

[EDIT2]

I have continued with my test about this "strange" DSK file. My DSK file in drive B has a size of 720 KB. I've used COPY"B:*.*" to copy all files from disk B to disk A. It has worked only for a part of the files, until I got the message "Disk full". After checking, the new size of disk in drive A is 359 Kb. So, this method allows you only to have DSK images of 360 KB. That explains why the dialogue on the emulated MSX in NLMSX doesn't include a choice between 360 Kb or 720 Kb ...

End of the mystery !

My sense of pure logic tells me that if you use different DISK.ROM with NLMSX
(maybe you have to define another FDD controller in NLMSX config), you will see the question whether to format single or double sided, and will be able to use 720K images.

But, of course, 360K is enough for saving state in Metal Gear 2, and the problem of this thread's author is solved.

I don't know whether NLMSX works this way intentionally, but it's a nice feature - you can use disk images with size of the program they hold.

my guess is: it's a bug, not a feature

Thanks everybody! By the way, both ways worked.