Looking for a memory counter rom (NMS8250)

Rookie (29)

22-01-2021, 11:49

Hi,

I recently upgraded the RAM of my NMS8250 to 1MB, but the boot screen still shows 128K. I know this is normal and that I must replace the ROM (IC118) for a ROM with a memory counter, the problem is that I don't know where I can find this ROM?

The only one I found on the internet is for a NMS8245 (https://www.msxinfo.net/download/nms8245-original-rom-with-m...)

Thanks
Hans

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Par sdsnatcher73

Enlighted (4307)

22-01-2021, 12:30

The ROM from the NMS8245 will work fine on the NMS8250

Par Briqunullus

Paladin (775)

22-01-2021, 12:46

Thanks. I just changed the subrom in my openMSX configuration. It works. Attention is in the details. Nice.

Par hansgoos

Rookie (29)

22-01-2021, 14:29

Just programmed the ROM found on the msxinfo.net site in a W27C512 and replaced IC118 with it. Then nothing is happening, and the MSX won't even boot.

Since the name of the ROM file is: nms8245Systemmemounterfastdisk.rom I tried to place it in IC117 (diskrom) and then the MSX boots normal (still showing 128K of ram), including a working diskdrive.

Par sdsnatcher73

Enlighted (4307)

22-01-2021, 15:17

Check the contents of the original ROMs. You may have to split the rom you downloaded and put the appropriate part in IC118.

Par meits

Scribe (6576)

22-01-2021, 16:59

I have this one in my 8250 and 8235 and it works a treat (up to 4096KB).

Par hansgoos

Rookie (29)

22-01-2021, 17:25

Thanks for your help.

I did split the 8245 file, and extracted the correct ROM now the start screen is showing

VIDEO RAM: 128Kbytes
USER RAM: 512Kbytes

But I have 1024K installed, so why only 512K is showing?

@Meits: in your picture I see only one line ' MAIN RAM: xxxxx' when using your ROM I have the same output as when I'm using the 8245 ROM (VIDEO RAM / USER RAM)

Par meits

Scribe (6576)

22-01-2021, 17:34

Same rom in different computer.

Par sdsnatcher73

Enlighted (4307)

22-01-2021, 20:06

You can try the BIOS files from sd-snatcher/FRS: http://frs.badcoffee.info/tools.html

Look for the MSX2newdrv. This combination has many updates and counts the RAM properly (I tested it on openMSX on a machine with 1024kB memory)

Par hansgoos

Rookie (29)

23-01-2021, 09:53