Diskrom mirror differences between openMSX en BlueMSX

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By Kwik

Expert (127)

Kwik's picture

26-01-2007, 14:42

The diskrom configuration of the Panasonic FS-A1F (MSX2) in openMSX differs from BlueMSX.

OpenMSX:

<TC8566AF id="Memory Mapped FDC">
<broken_fdc_read>false</broken_fdc_read>
<drives>1</drives>
<rom>
<filename>roms/fs-a1f_disk.rom</filename>
<sha1>141e61cc8e0e51382e508fbd77a34b778a4f8444</sha1>
</rom>
<mem base="0x4000" size="0x8000"/>
</TC8566AF>

BlueMSX:

3-2 4000-7FFF TC8566AF Disk Controller FSA1FDISK.rom

The openMSX configuration says that the size=0x8000, does this mean that page1 is mirrored in page2? In BlueMSX it does not seem to be mirrored.

Help!LOL!

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By Manuel

Ascended (18783)

Manuel's picture

26-01-2007, 19:12

I'm not sure, but I think you found some bugs in config files. It seems there are many more config files with 32kB size in them for the disk ROM. AFAIK all disk ROMs are only 16kB, am I correct?

By Kwik

Expert (127)

Kwik's picture

26-01-2007, 21:57

I'm not sure, there are a lot of diskroms in blueMSX that have an address range from 0x4000-0xbfff. Al diskroms i've encountered are 16kB, but perhaps some of them are mirrored in page2? This could be an advantage when transferring data to page1. We use this in our Nowind Interface, but i'm not sure if other diskroms do this as well...

By Manuel

Ascended (18783)

Manuel's picture

26-01-2007, 22:09

I think all are 16k, but some seem to be mirrored on page 2 indeed. At least some Philips machines. But I don't know the details, I'm not enough in these MSX details to tell.

By Kwik

Expert (127)

Kwik's picture

26-01-2007, 22:53

Hmmm, my 8280 doesn't seem to mirror...

By Manuel

Ascended (18783)

Manuel's picture

26-01-2007, 23:51

Neither does my 8245.

By Kwik

Expert (127)

Kwik's picture

27-01-2007, 00:22

I was wrong. The rom itself isn't mirrored, BUT the addresses that are connected to the FDC are! (that's 0x7FF8-0x7FFF which is also available at 0xBFF8-0xBFFF)

By Manuel

Ascended (18783)

Manuel's picture

27-01-2007, 00:26

How can I check this easily?

By zeilemaker54

Champion (341)

zeilemaker54's picture

27-01-2007, 09:02

Kwik is right.
The rom itself is not mirrored, but only the i/o addresses of the fdc. Most diskrom's (including Philips and Panasonic) are accutally using this feature to transfer from or to page 1 without using a sectorbuffer.
You can take a look at the msxsyssrc project at sourceforge.net. There are a number of different diskdrivers under the diskdrvs directory.

By Manuel

Ascended (18783)

Manuel's picture

27-01-2007, 10:43

Is this for all diskROMs? If not, for which ones is it?

By Kwik

Expert (127)

Kwik's picture

27-01-2007, 12:10

Here is a link to msxsyssrc (great work by the way!):
msxsyssrc.cvs.sourceforge.net/msxsyssrc/

The Panasonic FS-A1F uses these address:

1965 D7FF8 EQU 07FF8H ; DOR, b0 = 0 drive 0, 1 drive 1
1966 ; b2 = 0 reset FDC, 1 enable FDC
1967 ; b3 = 0 disable INTRQ and DRQ2 pins, 1 enable INTRQ and DRQ2 pins
1968 ; b4 = 1 motor select drive 0
1969 ; b5 = 1 motor select drive 1
1970 D7FF9 EQU 07FF9H ; TDR, b0 = TC
1971 ; b4 = FORCE READY
1972 D7FFA EQU 07FFAH ; MSR, Statusport FDC
1973 D7FFB EQU 07FFBH ; DAT, Dataport FDC
1974
1975 DBFF9 EQU D7FF9+04000H
1976 DBFFA EQU D7FFA+04000H
1977 DBFFB EQU D7FFB+04000H

So I guess the configuration of BlueMSX is not right! I'll send Daniel an email.

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