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Possibility PCI Floppy Drive Controller?

Agent Orange said:
That was my point, I don't consider PCI to be vintage. So, what you do is build a box where the mobo supports you needs. The Swiss Army Knife approach doesn't seem feasible without a large investment on someone's part. There are some fairly recent Gigabyte boards, for example, that support two floppies, 3.5 or 5.25, but you need to reach back to products prior to their 990 chipsets. Just takes a little research. Personally, I don't see where the problem lies. How you can be a computer hobbyist and a one trick pony at the same time so to speak.
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Which Gigabyte boards? I ask because one: I am not a big fan of their boards so I am not familiar with their offerings and two: that sounds like AMD boards/chipsets so you are really limiting yourself. This solution, IF easy to implement, would allow any MB w/ limited FD support to have full FD support (if my understanding of Chuck's statement is correct).

Again I have no idea how easy this would be or the cost involved but if it is on par w/ the XT-FDC I would say it is not prohibitive.
 
HoJoPo said:
How about using a PCI to ISA bridge, and an ISA floppy controller? You could even add a 98 pin or 62 pin connector to add an external ISA bus.

You might have to have driver or BIOS support for the bridge chipset, but it should work.
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Not really. Most of Intel's later offering for ICH do not support DMA access so even if your bridge chip does support DMA you still could not implement it. See here.
 
SomeGuy said:
A PCI FDC is not really possible. While it sort of could be done, it would be impossible to make it 100% hardware compatible as PCI lacks some abilities needed for full compatibility.
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Shadow Lord said:
A real PCI FDC is out of the question....
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Help me out here. While SomeGuy's points on BIOS compatibility are very valid, I don't believe there is anything preventing a '765 floppy controller from hanging on the PCI bus. PCI spec defines a bridge sub-class for ISA. The config space allows specifying an address window as an I/O space mapping. You can place a genuine uPD765 or any other ISA style FDC chip on a PCI card and it could appear at the native I/O address location and generate a compatible interrupt. With some glue logic, you could even have it think it was doing 8257 style DMA while doing PCI bus mastering in reality. Certainly PIO would work instead much like some early PCs that didn't have a 8237 (eg. Tandy 1000, PCjr, etc). What am I missing?

Beyond that, I'm a bit confused at the use case. A native hardware interface would only be useful for DOS programs running natively which is becoming less and less practical on modern hardware. A tweener machine or emulators supplement most of those needs.

For just accessing and imaging oddly low-level formatted floppies, flux-level emulators like Catweasel, Kyroflux, DiscFerret, etc seem to do the job and USB is more ubiquitous than PCI.
 
eeguru said:
I don't believe there is anything preventing a '765 floppy controller from hanging on the PCI bus. PCI spec defines a bridge sub-class for ISA. The config space allows specifying an address window as an I/O space mapping. You can place a genuine uPD765 or any other ISA style FDC chip on a PCI card and it could appear at the native I/O address location and generate a compatible interrupt. With some glue logic, you could even have it think it was doing 8257 style DMA while doing PCI bus maste.
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Hey you are the eeguru so your understanding would be much better then mine. ;) My very limited understanding was that Intel removed the circuitry needed for DMA in ICH 6 and higher. Is that incorrect?

As for use, I for one wouldn't mind having direct floppy access on my every day machine. In my ideal world I would fire up an emulator in 64bit win 7 and have it directly access the floppy drive HW like it currently does for CDs or 3.5" drives. Then in theory you could do most everything you needed to without using a second system. Is this possible? I have no idea but that is why I started the thread. If we have the HW I could see DOS box implementing support so you could pop in a real 5.25" booted disk and go.
 
Shadow Lord said:
Which Gigabyte boards? I ask because one: I am not a big fan of their boards so I am not familiar with their offerings and two: that sounds like AMD boards/chipsets so you are really limiting yourself. This solution, IF easy to implement, would allow any MB w/ limited FD support to have full FD support (if my understanding of Chuck's statement is correct).

Again I have no idea how easy this would be or the cost involved but if it is on par w/ the XT-FDC I would say it is not prohibitive.
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My backup is a Gigabyte GA-790FX-UD5P from about 2010. The CPU is an AMD Phenom II (Socket AM3) which runs at about 3.3 GHz. Memory is 4 GB of DDR2. The video is 2 XFX 5950's in CrossFire. The O/S is a dual boot XP and W10 lash-up. This board supports one floppy drive in any configuration; i.e. 3.5 720/1.44 or 5.25 /360/1.2. You can easily attach a 1.44 external floppy via the USB. Scarce chance of finding a recent mobo that supports more than one floppy. A good alternative to all of this is a PIII. My PIII tweener is an Intel board with the 815 chipset and a 1.4 GB Tualatin. It supports both, the 3.5 and 5.25 floppy's and the whole thing runs DOS and XP. Not so hot for browsing, however. Hope this helps as this is the best that I have to offer at this time. Good luck!

Late edit:

Most Gigabyte boards prior to the 990 chipset were rock solid. It was only after multiple failures on a new 990 board that I went with the Asus 990FX Sabertooth. The only boards that gave me any real problems from a few years back were MSI, and those were mostly BIOS related.
 
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Shadow Lord said:
As for use, I for one wouldn't mind having direct floppy access on my every day machine. In my ideal world I would fire up an emulator in 64bit win 7 and have it directly access the floppy drive HW like it currently does for CDs or 3.5" drives. Then in theory you could do most everything you needed to without using a second system. Is this possible? I have no idea but that is why I started the thread. If we have the HW I could see DOS box implementing support so you could pop in a real 5.25" booted disk and go.
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At present the best solutions for lobotomized "modern" computers are probably the Kryoflux and SuperCard Pro (Not too familiar with the Catweasel). They are USB devices but can be mounted internally if desired. They are not, however, very "direct". They do not appear as a drive letter in Windows or permit drag-and-drop file management. They work more like burning a CD - you prepare the image in advance and then write it, or read an image all at once and then extract files. The upside, however is they are not limited to MFM or even FM like normal FDCs. For example, they can read Apple II and Mac GCR disks or technically anything the drive itself can read and will preserve most copy protection schemes.

Theoretically, someone could write a tool for either of those to act as Windows floppy, but there would be a performance issue that both of these read and write data an entire track at once. Real FDCs normally read and write individual sectors. I'm not sure that the KF or SCP cards could be programmed to read and write individual sectors.

It sounds like what people really want is a real FDC. Some lobotomized "modern" EUFI systems reportedly already lack BIOS compatiblity and it is just getting worse, so you are stuck doing things through the version of Microsoft Windows approved for the system. And Windows support for floppy devices is already rather limited. Since you can already kiss IBM PC compatiblity good-by, there is no point keeping it compatible at a DOS/BIOS level. So a real FDC connected to a small on-board CPU might be do-able as that small CPU would do the heavy lifting of figuring out what format the disk is, and shuffling the data back and forth the the rest of the system. Aside from one read-only solution, I'm not aware of any like this out there currently.

It's time to start hording motherboards with real FDCs, especially those with dual drive and FM support.

Incidentally, I reviewed a few of the last motherboards with FDC support here: http://www.vcfed.org/forum/showthread.php?39615-Recent-motherboard-FDC-and-quot-legacy-quot-tests
 
One question, probably relevant:
How does the FDC on recent boards work, considering the chipset lacks DMA support?

See eg. MB-P4BWA - http://www.adek.com/PDF/MB-P4BWA.pdf
It has ISA slots, but without DMA.
It also has FDD connector - is there some DMA support exclusively for the FDC? Or maybe it works without DMA? But then, what about operating systems with FDC drivers expecting FDCs with DMA?
 
FDC-equipped motherboards aren't that rare, even today. I'm writing this on an AsRock 980DE3 AM3+ motherboard. Not exactly bleeding edge, but made in the last few years.
 
Chuck(G) said:
FDC-equipped motherboards aren't that rare, even today. I'm writing this on an AsRock 980DE3 AM3+ motherboard. Not exactly bleeding edge, but made in the last few years.
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Does it support 2 floppies or just one in any configuration?
 
If this PCI card worked in Windows 98, and supported 3 drives, I'd certainly use one on my tweener.

Alternatively two other projects I'd find just as useful though -
- generic version of XT-FDC ROM designed for newer PCs that allows drives 3 and 4 to run on a secondary controller that doesn't need a PCB / parts - just write the config and burn to a 2764.
- USB to 34 pin generic low cost kit adapter for noobs with the Windows 10, no BIOS support - just a way to write those binary disk images to DD and HD media. I'd use that too, often when I'm browsing for software I'm on a modern PC, having to transfer it to a tweener or my Netware server is just another step.
 
FDCs on modern chipsets work by using the LPC bus, which is a serialized version of ISA (and isn't given a connector), instead of using a PCI to ISA bridge.
 
bhtooefr said:
FDCs on modern chipsets work by using the LPC bus, which is a serialized version of ISA (and isn't given a connector), instead of using a PCI to ISA bridge.
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OK, but LPC does support DMA, so it should be possible to parallelize it back and get a fully-functional ISA.
However, those recent ISA motherboards lack DMA support for ISA slots.
Do they still support DMA in LPC? If not, how does it affect the FDC?
 
Xacalite said:
OK, but LPC does support DMA, so it should be possible to parallelize it back and get a fully-functional ISA.
However, those recent ISA motherboards lack DMA support for ISA slots.
Do they still support DMA in LPC? If not, how does it affect the FDC?
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According to Intel:

The ISA protocol allows for memory-mapped transactions to components placed on the bus. ... Indeed, on all I/O Controller Hubs up to and including ICH5 support these transactions. From ICH6 onwards, however, support for these transactions has been removed. As a result, it is not possible to support ISA memory mapped transactions on an Intel® Express chipset.
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We may be working at differing, if not cross, purposes.

If the idea is getting floppy support onto a modern machine, then the actual mechanism doesn't matter that much. In particular, it needn't even involve a real legacy floppy controller, just something that behaves in the same manner. For example, I know that John Wilson has been toying with the XMOS MCUs as an alternative FDC (the real things are only going to get scarcer). Actual connection to the system can be USB or even, say, Bluetooth--it needn't be PCI oriented--only that the host application (which could be running under DOSBox) be able to talk to it in what appears to be an ISA-compatible way.

The 765 isn't rocket science--it hails back to the mid 1970s. With a good choice of components and support software, there's no reason why it shouldn't be possible to have a functionally-equivalent device. Chips such as the National PC87200 and the PC8477 are just going to get scarcer.

Am I making sense?
 
Shadow Lord said:
According to Intel:
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That sub-section is organized under the LPC section. FDC wouldn't use memory mapped transactions unless you wanted to hang an option ROM on LPC. PCI is still feasible, but I'm not sure the point as proper BIOS and OS support are the real limiters.

Chuck(G) said:
Am I making sense?
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They are still plentiful on China brokers. I think we're still at least a decade away from exhausting the NOS. I even have 50 ISA super I/O chips with '765 "compatible" cores on the shelf. But you don't need to emulate the 765 itself if going the route of Kyroflux/Catweasel/DiscFerret, etc.
 
rosaage said:
www.ebay.com/itm/231804517259
Is it possible to make a custom driver for this so it can be used with 5.25" drives? Or is this technically impossible?
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Interesting. Never saw that device before. Still, I doubt it.

I'm guessing the firmware is probably limited in the same way as standard 1.44mb USB floppy drives. If you had the firmware source you might be able to smarten it up a tad but there is a second problem: If this relies on the standard operating system provided USB driver, the USB floppy spec only defines support for 3.5" 720k, 1.44mb, and Japanese "mode 3" disks. So you would need your own OS driver. Perhaps not impossible if the pieces were avaialble, but to meet the needs most people would have here (interfacing with emulators, dealing with copy protection, non MFM-encoding) would require a significantly different design.

(That said, you might actually be able to plug a 360k drive in to that device and read IBM PC disks, but it would likely get confused in some cases as it would still think it was a 1.4mb/720k drive - assuming it supports 720k)
 
eeguru said:
That sub-section is organized under the LPC section. FDC wouldn't use memory mapped transactions unless you wanted to hang an option ROM on LPC. PCI is still feasible, but I'm not sure the point as proper BIOS and OS support are the real limiters.


They are still plentiful on China brokers. I think we're still at least a decade away from exhausting the NOS. I even have 50 ISA super I/O chips with '765 "compatible" cores on the shelf. But you don't need to emulate the 765 itself if going the route of Kyroflux/Catweasel/DiscFerret, etc.
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Well you do, if you want to emulate functionality. Remember that the time-domain sampler MCUs are track-at-a-time. Easy enough for anyone to construct from junk box parts, but getting one to look and work like a legacy FDC is a pretty tall order.
 
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