MMC-ORIC

This is the right place to discuss on how to implement hardware vsync, adding a VIA or AY chipset, puting multiple roms, or how to design a new flash expansion card.
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Twilighte
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MMC-ORIC

Post by Twilighte » Sun Jun 10, 2007 11:44 am

I don't know (or can't remember) if anyone is already working on this project...

I wonder how possible it would be to make an MMC Read/Write interface for the Oric.
Perhaps use the MMC64 as a benchmark.

http://en.wikipedia.org/wiki/MMC64

On the C64 at least their is support for Disk and tape images but even just memory dumps would be really cool.
To me this would be much better than the ORIC IDE project, since MMC cards can ease the pain of transferring software from PC to ORIC, they can currently go up to 4Gb so could probably hold most of the Oric titles on one MMC.
As far as i know, the MMC64 used an FPGA to deliver a file menu system on bootup.

I would personally be willing to pay up to £100 pounds for such an interface.

If anyone can read German, their is a great technical spec here...

http://www.c64-wiki.de/index.php/MMC64

I also notice their is one for the ZXSpectrum called the Divide Plus, although that also has an IDE interface..

http://www.rwapsoftware.co.uk/spectrum/ ... orage.html

Twilighte Pleaing..

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Post by carlsson » Wed Jul 11, 2007 10:21 am

There is also GoMMC for the Acorn BBC/Electron series. I don't know which of these projects are most closely to Oric hardware, and they all are slightly different in implementation.
Anders Carlsson

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Post by carlsson » Wed Jul 11, 2007 10:37 am

Here is another one for the Beeb, which seems quite low-tech but cheap to build:

http://mmbeeb.mysite.wanadoo-members.co.uk/

Of course it would be another matter of how you access it from software.
Anders Carlsson

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Post by jede » Sun Jun 28, 2009 2:03 am

Hello,

are there others projects for a mmc cards on others computers ?

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Post by romualdl » Sun Jun 28, 2009 9:03 pm

Hi there,

Yes a lot of them (sd, cf or others) : commodore, amiga, atari st, atari 8bits, spectrum (maybe the simplest ever), acorn bbc, acorn electron, etc.

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Post by JamesD » Mon Jun 29, 2009 7:03 am

I looked at doing this. If you look around you'll even find the source for an FPGA SD interface for another machine. It would require minor modification for use with the Oric but the key pieces are there.
However without a DOS it's useless.
If there is a disassembly of an Oric DOS out there then it shouldn't be too difficult to proceed with a design.

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Post by Symoon » Mon Jun 29, 2009 5:58 pm

If there is a disassembly of an Oric DOS out there then it shouldn't be too difficult to proceed with a design.
There's "Sedoric à Nu" but it's in French. I'm not sure, maybe someone translated a few bits into English but I don't know where you could find it (assuming I didn't dream it).
I played with subdirectories in Sedoric, but I suspect having a new media would require much more complicated modifications (for me, at least).

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Post by Dbug » Mon Jun 29, 2009 6:16 pm

JamesD wrote:However without a DOS it's useless.
I totally disagree.
Having a SD/MMC based floppy emulator would be great.
Something that would just allow to store a gazillion of .DSK and select them, would make it possible to store all demos, games, etc... in a very compact way.
All that's required is a way to emulate a disk controller board, like the page 3 registers, the ROMDIS signal, and some logic to select the image disk files.

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Post by romualdl » Mon Jun 29, 2009 7:14 pm

Hi there,

As said before, the spectrum was the easiest since the first images of spectrum softwares were snapshots of the memory with the game loaded so petra's first CFcard for spectrum (ide indeed) was in fact based on a rom improvement and a few chips only.

Ok for the oric it's a bit harder but considering what some people around are able to do it would really be possible.
Once again Jeff's floppy controller emulator could be interesting to do that. I know last time I've been discussing with him (last year indeed have a look at Dbug's topic on floppy disc emulator) he finally managed to load some dsk file from his board during the night (here with a PC at the other end) with an oric disk controller needed, but he was working on a standalone version of his board for other machines and once again it's "only" a question of floppy disk controller.
The only solution I guess would be to harass Torlus (if you read this ;) ) to work on this instead of trying to make big bucks with an appleII2vga board or the like.


;)

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Post by Chema » Mon Jun 29, 2009 10:35 pm

Dbug wrote: Having a SD/MMC based floppy emulator would be great.
Something that would just allow to store a gazillion of .DSK and select them, would make it possible to store all demos, games, etc... in a very compact way.
All that's required is a way to emulate a disk controller board, like the page 3 registers, the ROMDIS signal, and some logic to select the image disk files.
YES. That would be easy and perfect, moreover with the difficulties on having a disc controller for the Oric...

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Post by JamesD » Tue Jun 30, 2009 3:21 am

Dbug wrote:
JamesD wrote:However without a DOS it's useless.
I totally disagree.
Having a SD/MMC based floppy emulator would be great.
Something that would just allow to store a gazillion of .DSK and select them, would make it possible to store all demos, games, etc... in a very compact way.
All that's required is a way to emulate a disk controller board, like the page 3 registers, the ROMDIS signal, and some logic to select the image disk files.
You disagree an SD interface is useless without a DOS?
Even a floppy emulator needs a DOS.

BTW, a plain old SD interface requires a clock and some serial shift registers. A floppy emulator requires a microcontroller, lots of new code, proper timing. Copy protection would be a real nightmare too.

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Post by ibisum » Tue Jun 30, 2009 1:35 pm

You disagree an SD interface is useless without a DOS?
Even a floppy emulator needs a DOS.
I think the point is, a properly functiong HARDWARE-emulator would just drop in on any Oric, and run SEDOric or so .. No?
BTW, a plain old SD interface requires a clock and some serial shift registers. A floppy emulator requires a microcontroller, lots of new code, proper timing. Copy protection would be a real nightmare too.
What about some 'external MCU' that can be glommed onto an IEC connector that reads DSK files from SD and spews them out over the Oric i/o and/or ROM lines to do a program load?

Feasible with an Arduino, no?

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Post by Dbug » Tue Jun 30, 2009 6:09 pm

ibisum wrote:
You disagree an SD interface is useless without a DOS?
Even a floppy emulator needs a DOS.
I think the point is, a properly functiong HARDWARE-emulator would just drop in on any Oric, and run SEDOric or so .. No?
Was the idea, yes. Or any of the other Oric DOS.
The hardware would be "something" that would pretend it is a microdisc controller, a jasmin unit, etc... then you just mount virtual floppies on virtual disc units, and you use whatever oric dos works.

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Post by JamesD » Tue Jun 30, 2009 7:24 pm

The devices that provide disk emulation are either very complex (Minimig) or simple serial interfaces (Atari & C64) disk emulators.

It's pretty easy for the serial interface drives since they just have to emulate the normal drive protocol over a serial port driven off of the pins on the MCU. But even these aren't perfect. Many games used fast loaders that download high speed code to the drive. Since the drive doesn't have the same processor these will not work. You'll also find that the DOS is already in ROM or at least partially in ROM on those machines.

The Minimig required a significant amount of work and it combines the SD interface and drive controller in a large FPGA + MCU.

What you probably want is emulation of drive controller registers in a small FPGA with a MCU that works behind the scene to do the real work. I'd also suggest providing a bypass of the emulation to allow new software to use the SD without limits of a floppy image.

That's more than I'd want to do and would cost more than a simple interface but you are more than welcome to go for it.

I have a compact flash interface (CFFA) on my Apple and it's pretty nice. However the Apple already has a DOS that supports mass storage devices and a lot of Apple games have already been hacked to load without floppy. The next version of CFFA is supposed to have floppy emulation. However, the floppy emulation is just an add on. The same could be done for the Oric.

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Post by Dbug » Tue Jun 30, 2009 9:27 pm

The thing is, if you go for the easy to implement pure SD-protocol, then you have -as you said- to develop a DOS for it, and then you need to have applications that uses it.

The floppy emulator part is more complex, but it provides immediate compatibility with existing software.

So I guess there is the usual problem here: Would such a device be designed for "evolutivity" and new developments, or as a practical way of using the existing Oric software.

I can see the problems that would bring having something detected as a real disk controller, but the advantages would be that for example all the low level code (like the demos and some games) based stuff would work out of the box.

If such a design require more complex hardware, like FPGAs, then well you have ground for other interesting things as well. I doubt a FPGA would be used at 100% by just having to emulate a floppy drive. You would probably have enough free gates for:
- filter the display system to add selection/menus
- add a digital tape player (so you would be able to replay TAPE files as well, would allow you to move your oric with every single oric game ever made, all on your small SD card)
- possibly emulate some other devices like joystick/mouse/light-pen/tablet/serial interfaces

So yeah, the cost could be high, but would that be much higher than the cost of an impossible to find microdisc unit ?

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