@manuel : got 'disk offline' problems with the 8230 and 8235. Probably worn drive belts because they're eating dust for some time now. Will get some new belts and try to fix them this weekend. I'll let you know as soon as I got them running again

Another request: if you have a National MSX with a diskdrive, it would be very interesting to have a dump of the slot with the diskROM, to see what the mirroring behaviour is for this machine.

msxrestarter: ah, damn belts again! But thanks for repairing and willing to help! I'll be awaiting your news

@manual: By looking at the servicemanuals of the VG8230,VG8235 and NMS8250 it seems that the VG8230 and VG8235 decodes FDC address only at 07FF8H-07FFFH, but the NMS8250 decodes the FDC at 03FF8H, 07FF8H, 0BFF8H and 0FFF8H (for saving some parts?) Can someone test this on a real NMS8250 ?

zeilemaker: see one of my previous posts: the 8250 mirrors the FDC registers in all pages indeed. Just like the SVI-738 and the Sony HBD-50!

@manuel : check your mailbox, first romdumps send

From the 8230 dumps, I see that there is no subROM mirroring at all and also no FDC mirroring at all. THanks msxrestarter!

What about the diskrom, is that one mirrored in all pages as well?

@manuel: exactly what I predicted from the servicemanual. But could you send me a copy of the 8230 roms ? zeilemaker54 (at) zonnet.nl

@dvik: no, diskrom is only active in page 1 (ROM is attached to the CS1 signal).

Quote:

From the 8230 dumps, I see that there is no subROM mirroring at all and also no FDC mirroring at all. THanks msxrestarter!

Indeed, the diskROM itself is not mirrored in the 8230. zeilemaker: feel free to send me an e-mail to remind me.

If there are more people willing to help: if you have an MSX2 or an MSX with built in disk drive, you could help us to find out about mirroring... We only have data about:
- Philips VG 8230 (soon also 8235)
- Philips NMS 8245
- Philips NMS 8250
- Philips NMS 8280
- Spectravideo SVI-738

If you have another machine, then the described procedure would definately help us to make emulation more accurate. (In the Philips range, an NMS 8220 would be nice... but data for any other machine is welcome as well!)

I also have a 8220, but how can I get the dump to disk ?
Can I use an external drive with interface, or will that influence the read out ?
If you show me how, I will also dump the 8220

@manuel, can you do a little table that shows the disk drives you have data about and what pages the FDC is mirrored into?

Yes, you can use an external drive. The dump of the slot with the disk drive interface would also be nice, but do tell me what kind of drive it is exactly (e.g. Philips VY-0010).
I'm interested in the slot with the subROM and the slot with the diskROM.
The subROM of the 8220 is also in slot 3-0.

You can find out in which slot the diskROM and/or subROM is located by using getrom.bin, which is on the same page as saverom.com. YOu don't need to dump the ROMs with that (they can be extracted from the slot dumps you make with saverom.com), but you can just see in which slot the ROMs are located.

In this program (start with: BLOAD"GETROM.BIN",R), you can see output like this:

No. Slot Description
1   0-0  MSX2 BIOS
2   3-0 MSX2 Extended BIOS
3   3-3 BDOS (Disk BIOS) Version 2.2

This means I'm interested in slot 3-0 (sub ROM) and slot 3-3 (disk ROM).

With this info, it should be possible to find out the FDC register mirroring and sub ROM mirroring behaviour of any MSX machine

@ manuel : romdumps of 8220 and 8235 are in your mailbox

Interesting, the FDC mirroring of the 8235 is the same as the '45: only in page 2, unlike the 8230 (no mirroring).

I made a simple overview of the data here: http://openmsx.sourceforge.net/techinfo/mirroring.html

@manuel: Very nice table interesting results too.