yes is another range, like daewo fdc, it uses IIRC 7BF8-7BFF and the bits of 7BFC has another meaning.

what do you write to address 0x7ffd? The motor on and off is bit 7 (think the note I wrote said bit 2).

I'm posting the note I sent to you earlier (fixed the wrong bit info). If someone find something else thats wrong, please comment on it :

Philips FDC:
------------
0x7ff8: R  Status
        W  Command
0x7ff9: RW Track
0x7ffa: RW Sector reg
0x7ffb: RW Data reg
0x7ffc: RW Side
0x7ffd: R  Drive
        W  Bit 0-1: Val=0: drive 0
                    val=1: drive 1 
                    val=2: drive 0 
                    val=3: none
           Bit 6:   Led on/off
           Bit 7:   Motor on/off
0x7ffe:
0x7fff: R  Bit 7=Data Request 
           Bit 6=IRQ


National FDC:
-------------
0x7f80:           R  Status
                  W  Command
0x7f81:           RW Track
0x7f82:           RW Sector reg
0x7f83:           RW Data reg
0x7f84 - 0x7f87:  R  Bit 7=IRQ
                     Bit 6=Data Request
                  W  Bit 0-1: Val=0: none
                              val=1: drive 0 
                              val=2: drive 1 
                              val=3: none
                     Bit 2:   Side
                     Bit 3:   Motor on/off

0x7f80-0x7f87 is mirrored to 0x7fff

SVI FDC:
--------
0x7fb8:  R  Status
         W  Command
0x7fb9:  RW Track
0x7fba:  RW Sector reg
0x7fbb:  RW Data reg
0x7fbc:  R  Bit 7=IRQ
            Bit 6=Data Request
         W  Bit 0-1: Val=0: no disk (?)
                     val=1: drive 0
                     val=2: drive 1 
                     val=3: no disk (?)
            Bit 2:   Side


Microsol FDC (I/O mapped):
--------------------------
0xd0:  R  Status
       W  Command
0xd1:  RW Track
0xd2:  RW Sector reg
0xd3:  RW Data reg
0xd4:  R  Bit 7=IRQ
          Bit 6=Data Request
       W  Bit 0-3: Val=1: drive 0
                   val=2: drive 1 
                   val=4: drive 2 
                   val=8: drive 3
                   other: none
          Bit 4:   Side
          Bit 5:   Motor on/off

Quote:

Is there hardware available with rewriteable roms?

For example IDE interface can be flash upgraded. (Flash update utility and ROM:s are available in www.msx.ch)

I think it would be a very bad idea to use checksums of ROMs. There are way too many diskROMs floating around and any change in any of them will break the mapping directly.

@Dvik: Thanx, but are you sure, that bit6 is the led? In BlueMSX the led is now always off. I wonder, if BlueMSX cares about, if the motor is on or off, when the FDD is been accessed.
I still didn't get the FDC routines working on my real MSX and I am not sure, if I already have the correct information. I think Flyguilles means, that it has the SVI FDC (#7fb8-...) or is it again another one? (@Flyguille, you wrote #7bf8-...?). Here I use bit3 of #7fbc to activate the motor.
Another question: When I am in the "machine editor" tool of BlueMSX and want to start the VG8235 I get the message "Emulator can't be started". Do I need some roms here?

Prodatron, oh sorry I means 7fbx, and it is another, daewo 5 1/4 but don't worry about that one, it is useless anyway because there is no more 5 1/4 working disk but some few connected a 3 1/2 drive and go on!!!! formatting 1.44mb disk with 360kb images

* 7FBC(3)=1 MOTOR ON/OFF
* 7FBC(0)=1 A:
* 7FBC(1)=1 B:
* 7FBC(2)=x SIDE selector

* 7FBC(6)=1 BUSSY (for the wait loop)
* 7FBC(7)=1 EOF (stop reading/writing that means the 512bytes was done)

the other is just WD compatible

formats 360KB 5 1/4 40 tracks 9 sects 2 sides

to detects these units are EASY

just reading or writting
* 7FBE accs selects rom 1 (always diskrom)
* 7FBF accs selects rom 2 (always cp/m rom or nothing in the socket)

so, just reading these addr, and checking if the rom changes ... done

Quote:

Another question: When I am in the "machine editor" tool of BlueMSX and want to start the VG8235 I get the message "Emulator can't be started". Do I need some roms here?

blueMSX comes with the roms of all the generic machines; to run a specific machine, you need to download the complete configuration (including the specific roms) on the Resource page of the website and to unzip the file in the Machines subdirectory of blueMSX.

Prodatron, you're right, blueMSX doesn't care about the motor on/off.

Thanx to both of you, this already helps.
One question: Why is #7FBC needed for reading (busy, eof)?
These two bits should already be present in the status register (#7fb8), shouldn't they?

Quote:

Thanx to both of you, this already helps. One question: Why is #7FBC needed for reading (busy, eof)? These two bits should already be present in the status register (#7fb8), shouldn't they?

yes, that info is correct, i thinks there is a redundancy, but using those bits is how does the diskrom

by the way, it is WD 1772 PH

Quote:

I think it would be a very bad idea to use checksums of ROMs. There are way too many diskROMs floating around and any change in any of them will break the mapping directly.

First: define 'way too many'. Assuming you use a simple checksum you'd talk about maybe 2 or 4 bytes per ROM. For this to be anything remotely close to a 'problem' you'd have to talk about hundreds of disk ROMs, which as far as I know is nowhere near the actual number. You can of course poll the driver (which is what I suggested in case the checksum didn't match) but this requieres loading all the drivers and polling each of them to see if they report as expected. Apart from that, I wonder if it's possible to get a identifyable reponse from all these FDCs without causing disk-access to occur. If that is not possible, you'd have drive-access which is something you'd want to avoid. Anyhow, checking for the most common disk ROMs using a simple checksum and only polling drivers if that first check fails seems like the most logical method to me.

Thank you, flyguille! So I don't need to be afraid, that the bits in the normal status register are not working.
Regarding rom switching, is it also an usual feature of the disc roms? When I switch between diskrom and cp/m (or nothing), the ports at #7fbx are always available?

@Sonic_aka_T: Maybe there is a way to test the different FDCs without disc access. When switching of the motor and trying to execute a command, you should receive a "drive not ready" error. Maybe this is already enough for the detection. I am afraid, that making all the checksums can be a lot of work.

Yes they are.

And no,i thinks it is not usual feature .