Diskrom mirror differences between openMSX en BlueMSX

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Por Manuel

Ascended (18704)

Imagen del Manuel

30-01-2007, 22:10

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 Smile

Por zeilemaker54

Champion (338)

Imagen del zeilemaker54

31-01-2007, 09:25

@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 ?

Por Manuel

Ascended (18704)

Imagen del Manuel

31-01-2007, 09:58

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!

Por msxrestarter

Master (224)

Imagen del msxrestarter

31-01-2007, 22:38

@manuel : check your mailbox, first romdumps send Smile

Por Manuel

Ascended (18704)

Imagen del Manuel

31-01-2007, 23:42

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

Por dvik

Prophet (2200)

Imagen del dvik

01-02-2007, 02:51

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

Por zeilemaker54

Champion (338)

Imagen del zeilemaker54

01-02-2007, 08:11

@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).

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

Por Manuel

Ascended (18704)

Imagen del Manuel

01-02-2007, 09:43

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!)

Por msxrestarter

Master (224)

Imagen del msxrestarter

01-02-2007, 16:17

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 Wink

Por dvik

Prophet (2200)

Imagen del dvik

01-02-2007, 17:58

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

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