Since there isn't anything here yet, let me put a little basic info out for anyone that is interested.

The CoCo3FPGA project has a yahoo group at: http://groups.yahoo.com/group/CoCo3FPGA/

The mailing list is low traffic but plenty of helpful folks around. Gary Becker is the primary developer and he has done an amazing job at creating a very CoCo-ish machine that runs on modern hardware. This is the CoCo 4 that I've always wanted, although others have their own ideas about that hehe

Most of the people using CoCo3FPGA use the Altera DE1 FPGA board. It costs about $150, less if you can qualify for the educational program. Gary does support a Spartan board and there are some ports to others but if the primary purpose is to run CoCo3FPGA then I think the DE1 is your best choice. As a side note, you can also use the DE1 as a fairly convincing Apple II, Amiga, IBM PC XT, and others.. just load a different configuration, but really why would you when you can have a CoCo?

So.. what is it... well I am probably not the most qualified person to explain exactly what FPGA is, but essentially this is reconfigurable hardware defined by software. I'm sure google can provide details. Once the FPGA is configured as a CoCo, it essentially is a CoCo in many regards. No emulation software is running behind the 6809, instead the FPGA basically is a 6809 (plus all the other chips found in a CoCo). In fact, the only software on the FPGA board at power on is an unmodified CoCo 3 ROM and Disk Basic (a slight lie here, will explain below). This provides many advantages over an emulator running on a PC, a major one being that connecting real CoCo peripherals is possible. Some of us have also found that using the CoCo3FPGA just feels more "real" than running an emulator.

There are also advantages over a physical CoCo. For one, the CoCo3FPGA can run at up to 25Mhz. It connects directly to a VGA monitor and uses PS/2 keyboards. Audio is provided on a standard 1/8" jack (and an Orchestra 90 is built in). But wait, there's more... Gary has addon boards for the DE1 in the works that provide real joystick ports, bitbanger and 6551 serial, 2MB ram, an extra PS/2 for a mouse, and other surprises. I've been testing out one of these here and will be demoing it at the Cocofest. *Really* cool stuff.

CoCo3FPGA uses DriveWire for storage, but it's better than DW is on a real CoCo. It runs at 4x the speed (460kbps) and rather than requiring special ROMs or OS9 drivers, the DW protocol is processed with an axillary processor (hence the "lie" above.. there is a little bit of other software running on the board) The DW virtual disks are presented to the CoCo as a standard FD501 and drives. This means no more compatibility problems with software that writes directly to the hardware. Stock OS9 disks without any DW specific modules will boot fine. There is an optional FPGA/DW specific module to enable the enhanced features in DW4, but it is not required for basic disk support.

I'm sure I've left some things out and explained many things poorly, but hopefully this is a starting place for those who are interested. Here's a short video of CoCo3FPGA on a DE1 in action. If anyone would like to know more feel free to ask, or try joining the Yahoo group.

Aaron,

That's a terrific write-up!. That's probably going to be my winter project - DE1 CoCo-style!

I'm curious; wonder how a Propeller would handle a CoCo... (not that I'm anywhere skilled enough to do it...)

EDIT: After looking at it, I doubt it could...

Looks cool but the bare exposed circuit board gives me pause. What happened to good O'l casings for crying out loud? And what about the Next CoCo project which was supposed to be FPGA as well?

This particular board is designed for use in college level academic courses, not consumers. Ideally, as technology advances and things get smaller, we could fit the whole thing into a regular CoCo case.

I'm not aware of any other FPGA CoCo projects, active or past, but that doesn't mean there hasn't been one. AFAIK Gary is the first and only person to deliver a useable CoCo on FPGA. John Kent designed the 6809 CPU used in CoCo3FPGA, he also has an FPGA 6809 based system called System09 which is fun to mess with. System09 runs FLEX and doesn't have the CoCo specific hardware, I suppose it's more like the SWTPC was.

If I remember right, there was an FPGA CoCo 1 that Mark McDougal was working on. He has a bunch of FPGA stuff on his site. I don't know if he has done anything with it since the CoCo3 FPGA project surfaced.

PunkMaister,

The CoCo3FPGA project is still (and probably always will be) a pretty DIY kind of thing. In general I don't mind having the circuitry hanging out in the breeze. I think it's kinda cool. However, I had an old CoCo 3 case lying around from when I repacked one into a mini tower case back in the day. So I put my Spartan 3 board into the CoCo 3 case, along with a mini PS/2 keyboard. I've got pictures up on my blog: http://8littlebits.wordpress.com/2010/12/18/an-old-case-for-a-new-coco/

I'm hoping to get a desktop CNC mill soon, and plan to try experimenting with making project cases for things like this out of sheet metal, wood, and plastic. I'd like to try my hand at a case for the FPGA development boards that looks plausibly CoCo-like. No promises yet.

JCE

That is really cool! Not sure if the DE1 could fit in a coco3.

No but it could fit into a cool minitower case. I'd just love to see this turned into 2 editions one that is sold as a completely stand alone CoCo computer and another that is sold as an attachment to an existing PC or Mac.

Santa was a little late but he brought me a DE1 board today!
I've wanted to learn VHDL and Verilog and the old PLD dev board I have just didn't have enough gates and required too many add on boards to do what I wanted, so I took the plunge.

The board seems to be ok, all tests passed.
Sadly, one of the developer disks was unreadable so it's going to limit what I can do until I can download everything or until I receive a new disk.

I looked at the docs and the info on the yahoo group and it doesn't look difficult to configure.
It looks like there are just three steps to configure the board as a CoCo3.
Erase the FLASH memory.
Program CoCo 3 ROMs into the FLASH memory.
Program the CoCo 3 hardware into the FPGA.

Section 4 of the User Guide tells how to erase the FLASH.
A comment posted to the yahoo group seems to indicate you need to erase the entire FLASH device before you program it instead of just the area you are going to download the ROMs to.

Section 4 also tells how to do a sequential write to the FLASH memory.
That should be how you write the ROMs to the FLASH.

Section 5 tells how to program the FPGA, there are two choices, JTAG and AS. If you want to temporarily program the FPGA, use the JTAG instructions. If you want it to come up configured as a CoCo 3, use the AS instructions. I think most people will opt for AS.

It really doesn't look difficult to do, certainly no worse than what I've done on in circuit emulators.

Just one little comment...
If someone intends to run many 8 bit computers out of the FPGA, it would probably be better to have a version that stores the ROMs in RAM instead of FLASH.
But perhaps that would be better left to one of the many FPGA boards designed just for that purpose.

I plan to repack the DE1 or a similar board in an old XT clone case. I'd eventually like to eliminate a lot of the old computers from my collection and just use a single re-configurable FPGA based machine.