Nms 8250 bit error

Master (232)

18-03-2023, 14:14

One of my msx (Philips nms 8250) i have, has an issue,
With testmap i came to this message, does my computer has a bad ram?

I can load games and programs by disk, some games are acting strange knightmare, yie are kung fu 2, and other work just fine, I don't quite get it, but i suspect a bad ram.

By Wlcracks

Hero (565)

18-03-2023, 15:11

in wbass2 with the "page" and "mon" check manually by entering values and look if they are correct.

By AndreV

Master (232)

18-03-2023, 15:29

I have put wbass2 on a disk, tomorrow a'll try it, i have no more time now (get to work) .

By AndreV

Master (232)

19-03-2023, 11:58

I get this kind of readings, i don't know what is means

By Wlcracks

Hero (565)

19-03-2023, 12:29

I think looking at the screen of "testmap" (i never seen this program)
page 2,3-2,1
mon &h8100
and if you change the hex code of the address it should view the same as you entered.
you need some basic MSX knowledge for this, sorry.I can only help you with a tip how to verify the memory.

By AndreV

Master (232)

19-03-2023, 13:18

Thnx for the help, actually i can barely play a game and more knowledge of program or basic i don't have, sometime ive a problem or a defect arises i can fix it whit some luck, trail and fail till something does work.

By Wlcracks

Hero (565)

19-03-2023, 15:04

ok.
goto msx basic
poke&h8100, number
? peek (&h8100)
this result should be same as "number"
number can be 0-255

By AndreV

Master (232)

20-03-2023, 08:20

The poke results in the number I typed, maybe its not the ram, can the z80 chip be a little dodgy insteat of the vram chips?

By Wlcracks

Hero (565)

20-03-2023, 15:46

Look like "TestMap" gave a result of the memory mapper.

By ro

Scribe (4963)

20-03-2023, 16:14

Well, don't you just love those screenshots of that great ide
I'm not sure what testmap does, I think it does a check on all 8 memory mapper segments found in slot 3-2 and it stumbels on segment (block) 1. Which, in your case, should be the BASIC program. That's prolly also the reason why it check on RAM adr #8100 instead of #8000.. gheh. (nevermind that)

So I can't really conclude anything other than TestMap isn't happy. Sorry

By AndreV

Master (232)

20-03-2023, 17:24

Ok, basic is also on a rom, so its posibble that, that basic rom let the computer act strangly? I tried out the disk on a other msx and no problemen, i think if the ram is bad, i don't get a game loaded at all, or strange charaters on screen , black screen ec.