NMS-8250 - Expansion carts don't work?

By puckipedia

Supporter (2)

puckipedia's picture

19-04-2017, 16:53


I'm new to the world of MSX and just got a Philips NMS-8250 (1 floppy) and while it does anything video-related perfect (MSX-DOS runs, Knightmare works, both SCART and composite output video), there's no audio (update: /someone/ didn't plug the audio connector back into the analog board...) I also have both a 512k memory mapper and an MSX-AUDIO compatible cart (both from MSX Club Gouda), but both don't do anything. I also opened up the machine but there doesn't seem to be anything off. Any idea what the issue could be?

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By Manuel

Ascended (14125)

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19-04-2017, 23:01

How did you come to the conclusion that they don't do anything? What did you try? And what did you expect?

For the memory mapper, run memory test software. The MSX-AUDIO you are talking about is probably an MSX-MUSIC right? (FM-PAK?)

By Grauw

Enlighted (7012)

Grauw's picture

19-04-2017, 23:46

Note that most if not all MSX2 computers actually don’t count the memory when they show the amount on the boot-screen. It’s hard-coded in the BIOS. You can confirm with openMSX for the NMS8250, openmsx -machine Philips_NMS_8250 -ext ram1mb; it will still show 128K RAM even though there definitely is 1152 MB present. So your memory mapper likely works fine.

As for MSX-MUSIC, you can usually start the internal software with _FMPAC or _FMPAK (depending on the maker). And play games which use it, e.g. Xak (fantastic soundtrack), or music disks from the scene.

By RetroTechie

Paragon (1418)

RetroTechie's picture

20-04-2017, 01:35

Welcome here, puckipedia! Smile

The RAM can be checked either by running some test software, or by running software that needs the extra RAM. As for the first option, a very quick check can be done by knocking in the following from BASIC:

poke &hf676,1: poke &hf677,193: poke &hc100,0: new
10 for n=255 to 0 step -1: out 254,n: poke &h8000,n: next n
20 for n=0 to 255: out 254,n: print n; peek (&h8000): next n

(use the STOP key to pause output as needed)

Notice the 2nd column of numbers returned.
If you see numbers 0..7 repeating, that (most likely) means the NMS8250's internal 128KB mapper is in use.
If you see numbers 0..31 repeating, that (most likely) means the 512K mapper is used (and thus working - at least somewhat).

Btw good questions, Manuel! Wink

By puckipedia

Supporter (2)

puckipedia's picture

20-04-2017, 14:15

Manuel: I tested with a copy of Unknown Reality, which only showed the music player (which didn't make any sound, no matter how I plugged in the music cartridge). Though apparently after I tried _FMPAK (which I didn't try before I think? only _FMPAC and a few others) it apparently worked.

RetroTechie: According to your code (which, I guess, just writes the page number to the corresponding mapper page, then reads it back) it showed that the internal mapper was in use. After opening up the cartridge and cleaning off the contacts ... it started to work, and I can now play Unknown Reality without any issues! Now just to find a few fun games on floppy (and maybe develop some of my own ;P)

And yeah, I probably should've tried cleaning the contacts of both the cartridges before blaming the MSX2 itself... Well, everything works fine now! Thanks for the help, everyone!

By gdx

Paragon (1950)

gdx's picture

21-04-2017, 00:59

The contacts of our cartridges need cleaning from time to time and sometimes have to be inserted several times to work properly. Cartridge slots Contacts are getting old.

My MSX profile