About msx Floppy Disk - Low level access?

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Por Manuel

Ascended (18845)

Imagen del Manuel

28-10-2007, 18:06

AFAIK, very few softwares skip the disk ROM. I only know two: FastCopy by XelaSoft and SymbOS.

Most of the time people don't want to waste time making 3 or more different drivers for the FDC's out there...
Those games do not access floppy hardware. They just use the sector read function(s) from the disk ROM.

Por mth

Champion (507)

Imagen del mth

28-10-2007, 18:12

I think all Japanese and European software uses the disk ROM, except for disk tools like FastCopy and Formula and operating systems like SymbOS. A lot of Brazilian software accesses the FDC directly though, these are I/O port based FDCs, like the DDX 3.0 that is emulated in openMSX.

Por turbor

Champion (499)

Imagen del turbor

28-10-2007, 21:02

I get the impression that PingPong gets confused between 'managing the HW directly' or 'using the BIOS/BDOS to do sector based access' if he talks about games like aleste. It might be caused by the fact that those sector based software will not react like a normal floppy if you try to use standard MSX-DOS/BASIC files based commands.

@PingPong, if you want to cover 99,9% of all software then having sector based, using a NoWind/normal disk ROM in a memory mapped model will do the trick.
If you want to have those disk tools like FastCopy or Brazilian I/O port based FDCs software working then you're in for quite the challenge...

Also IIRC, the memory on the Nowind is also needed to act as a buffer due to transfer speeds on the USB cable. You can not possibly pass all the i/o of the 3.5 MHz MSX bus to a PC over a USB cable and then have all signal processing done on the PC.

Por PingPong

Prophet (3898)

Imagen del PingPong

28-10-2007, 21:11

@mth, @manuel. thx, But, if for example i insert two cartridge adapters on a msx1 without drives, (in order to have two disk devices, A: & B: ) why those adapters do not conflict? the I/O addresses aren't the same?
The same does not apply to memory mapped disk devices?

Por turbor

Champion (499)

Imagen del turbor

28-10-2007, 21:55

PingPong: if they are memory mapped then the slot-select will make sure that they can both react as needed. Only the cartridge that is active in the slot that is being written to will react.
If they use I/O instead of being hardwired to a certain memory region then you'll have a problem: both will react to the same I/O's since I/O is seen by all devices on the MSX-bus and the result of both interfaces answering at the same time can be 'annoying'.
Depending on the IC's and the MSX results can be anything from: "fastest cartridge wins" to "both get corrupted floppy's after a while" till "short-circuit and you blow up both cartridges and the motherboard of your MSX" Crying

Por PingPong

Prophet (3898)

Imagen del PingPong

29-10-2007, 13:10

so maybe it's better to adopt a memory mapped layout.

Por Kwik

Expert (127)

Imagen del Kwik

02-11-2007, 01:11

Also IIRC, the memory on the Nowind is also needed to act as a buffer due to transfer speeds on the USB cable. You can not possibly pass all the i/o of the 3.5 MHz MSX bus to a PC over a USB cable and then have all signal processing done on the PC.

That's not entirely correct. The only memory Nowind contains is flashrom. This is used to store a modified version of the diskrom. The remainder can be used as a ROM disk. It is true though that we do not pass all i/o on the MSX bus to the PC. We simply write the bytes to a memory mapped location, that is connected to the usb chip.

By the way, development is still ongoing. Right now we are solving some issues in using the interface with linux and mac.

Por PingPong

Prophet (3898)

Imagen del PingPong

02-11-2007, 18:41


By the way, development is still ongoing. Right now we are solving some issues in using the interface with linux and mac.

@KWik:In that case, is useless thinking about an alternative floppy disk interface, but i'm very interested about nowind, instead.
I'm a freelance c++ dev (win32, and a bit of linux) and if you like help i will feel happy to giving my contribution in speeding up the developing. Today, msx computer have no valid alternative to floppy disk because there are not many devices working and because the physical media is extremely obsolete. (-> it's not easy to find/buy a set of floppies)
Also consider that while i have a very low level of knowledge of today's electronic , the opposite is true about the electronic of 20 years ago. I can also code in z80 mc.
Let me know at spambin dot AT tiscalinet dot it, if you are interested.

Por Manuel

Ascended (18845)

Imagen del Manuel

02-11-2007, 19:01

PingPong: you're not interesting in helping out an emulator project, are you?

Por PingPong

Prophet (3898)

Imagen del PingPong

02-11-2007, 19:57

PingPong: you're not interesting in helping out an emulator project, are you?
the nowind emu?. No, thx, there are already two good msx emus (openMSX ! cross platform ! Cool ) e blueMSX (nice and easy to use) Both are extremely accurate and in a final stage (= completed) of their evolution, so why another emu?

I think both emus have not much to improve, because their are near to perfection.
the first is also multiplatform, allowing MSX to live on extremely different machines. So i think what i can gain from another sw msx emulator? I already have all i wish. And much more. (for example openMSX also emulate V9990 that in IMHO is not a MSX HW, instead some kind of strange beast that allow super performances on msx, but in this way we loose the feeling of those old computers, so imho it's not a required thing to emulate)

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