TG68 - The Open Source Minimig CPU into the FPGA

[MiniMorph]

I just thought I would let people know that I am working on an improved boot loader based on the Minimig one.

The aim is to extend the excellent work done by Dennis and Tobiflex, so the Minimig can do more and also so a board like the Minimig board can be made to run more cores.

The one thing I plan to add if I ever get it going is Ethernet to the Minimig.

I think Tobiflex has worked on a Amstrad CPC core in the past and there are many other cores out there that can benefit from been run on a board like the Minimig one.

I am no expert FPGA coder at this time so I would have to get Tobiflex's core running on one of my two Xilinx based boards.

I notice Tobiflex's is running on Altera based boards at the moment. I hope I can get hold of the HDL and get it ported to my boards. I may be able to get that done.

I would really like to try anyway.

You can see what I have been up to on my website here :-

http://minimorph.com/forum/viewforum.php?f=42

I have non of this working at this point. I am actually still waiting for a Dev kit to arrive for my chosen Micro controller hardware platform.

The one bit of good news is that the tool chain I am using is totally open source and free to download, unlike the Hitech tool chain used on the current Minimig boot loader.

I plan to put the code up on Source Forge on maybe Open Cores when I have it working.

What do you all think ?

Feedback welcome.

[MiniMorph]

Hi freqmax,

You have exactly the same idea as I have of running more cores on a FPGA board and how to achieve that.

The current PIC18 series code would need modifications to make it suitable for running more cores and that is just what I am working on.

The MiniMig board is not ideal for running other cores however. The on board 68000 is not much use if your core needs a 8086 or a Z80 !

The FPGA on the Minimig may be too small to run some more complex cores.

The Minimig board should be great however for emulating things like the Atari ST, Mac Classic and Sinclair QL.

It should easily be able to run older computers like the C64 and Spectrum.

Tobiflex's new version with a 68000 in the FPGA is much more suitable for running other cores.

I think Gigabit on an Amiga class of computer would be a waste of time. It would never be able to keep up with the data.

The new Micro controller I am developing for my version of the boot loader has Ethernet built in, so no extra PHY is not required. This will add an Ethernet Capability to both the Boot Loader and the FPGA and use no extra FPGA pins. It will also allow the boot loader to retarget classic ports such as RS232 and Parallel ports over the Ethernet.

The chip is also much more capable than the 18 s series PIC, so more suited to a board that can run many cores.

Lastly the tool chain I am using is Open Source and Free to download, which I think is important for an Open Source community project.

All the best.

[MiniMorph]

To answer your questions.

1) Yes, sure the Luminary chip could be used a a co-processor.  I was really planning on making the Luminary chip emulate things like Tape Drives, Floppys & Hard Drives and then also to hook the legacy ports to Ethernet. I think these tasks are best handled in software and as the boot loader would provide it capabilities to all cores it. The sort of thing that would be possible is downloading a program directly into your core from the internet.

2) The Luminary chip has no USB, that is provided by an ftdp chip that acts as a JTAG Interface and USB to serial port converter at the same time. It should be pretty easy to get Ethernet communications through the Luminary chip from the FPGA core. Simpler than emulating hard disks and the like. I anticipate using UDP, TCP/IP, TFTP and FTP communications. HTTP stuff is also possible but I do not see what you could do with that.

3) I am no expert of SDHC, if you can talk to an SDHC card using SPI then I guess it can be made to work. I will do more digging. I would think 2GB is quite a lot of software for an Amiga Classic .

4) I think $13 is pretty good for what it does. The evaluation board is also very good value. i just wish mine would turn up !! The tool chain is open source and free to download which is nice too.

The actual part I would use on a PCB would be the LM3S6918 Micro controller. I also plan to make use of the A/D converters and Real Time clock capability.

[MiniMorph]

Cheers.

freqmax wrote:
13 USD for another chip is a bit. Esp considering the FPGA is 25 USD..
I don't propose 1 Gbps for Minimig. But it might be easier to source those chips etc..
Because 10M ethernet can't be accomplished without external hw, and 10/100M chips are the slowest ones that exist. 10/100M is the best choice.

13 USD is just the list price I would hope to get it cheaper than that. It is not that much money to add 10/100 Ethernet to the board along with all the rest it can do, like real time clock and A/D's.

If there were a Mini Morph 2 then I am guessing that the 68000 would be run in the FPGA itself and thus a more expensive than 25 USD FPGA would be required.

I am glad you approve of 10/100 Ethernet, I think it would be fine too, and with a 50MHz Cortex M3 processor to pick up the Ethernet it should fly !

I will continue with development of my Minimorph Bootloader. I let people know when I have it working in this forum if there is interest. In the meantime I will post my progress on my own site as mentioned above !

P.S. does anybody know where to buy Altera DE1 boards in the UK/ Europe ?

[MiniMorph]

I have had a lot of trouble with parcelforce charging a nearly  £20 handling fee for stuff from outside of the EC. I now try and order from Europe.

[MiniMorph]

I would like to order a Altera DE1, but I hate those fees.

The fee would be the same if I order 5 DE1's as if I order 1 so that would save some cash.

Is there 4 more people in the UK or EC that would like a Altera DE1 I will order 5 and sell the other 4 on.

So are there 4 others who want a DE1 ?

[MiniMorph]

Is this an Altera DE1 :-
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=544-1736-ND

Looks like it to me !!

[MiniMorph]

Great work putting the PIC stuff into the FPGA Fabric.

This is great if all you want is a Minimig.

The Idea of the Minimorph Boot Loader is that I can load many different cores into the FPGA.

The ones I am planning for sure is :-
ZX81 (ZXGATE),
VIC20 (FPGA Arcade),
C64 (FPGA64) ,
Spectrum (ZXGATE),
Amstrad CPC by TobiFlex I belive
Atari ST by Wolfgang Förster,
Amiga (Minimig)

This would make the project like the www.mess.org of the FPGA world

I think using a micro controller Boot loader is the easiest and best way of doing this.

I want to add one platform myself. I will not mention that until I make some progress !

It will be possible to "hand" the MicroSD card over to the FPGA after loading by pin sharing between the micro and FPGA. The Micro controller can offer "Services" to the FPGA, like Tape Emulation, Floppy Emulation, Hard Disk Emulation, Telnet, Serial to Ethernet Conversion, TFTP, FTP, TCP/IP and so on.

I know I can make all this work. In my professional life my work is 90% firmware.

The main thing my work will add to the Minimig is Ethernet.

I would like to order an Altera DE1, is this board OK for the Minimig ??

If you need help with the Z80 firmware I can help there let me know with a PM.

I will port my version of the Boot Loader to your embedded Z80 chip given the chance !

[MiniMorph]

I think Tobiflex will release cores for both the DE1 and the DE2, so you can choose the have the 150 USD DE1 or the 499 USD DE2. I am pretty sure any core that will run on the DE1 can be easily ported to the DE2.

My Boot Loader would be the same for both anyway. In fact I expect my Boot Loader could be used on pretty much any FPGA board suitable for running the cores. I accept there would be less need for the the Ethernet of the MiniMorph boot loader on the DE2, but heh better 2 than none.

I already have the Mac Classic in mind for later. Do you know of an open FPGA version of the Mac Classic ?

I do not know hardly anything about the Sun. I did use a 68000 workstation in the 80's at college. It was for designing logic for Programmable chips . I am not sure if it was a Sun however. Do you know of any FPGA projects for Sun Workstations ?

[MiniMorph]

Well done Tobiflex and Dennis.

A Historic day in the Retro FPGA world to see such a fantastic  core that runs on a virtually unmodified PCB that only costs 150 USD. Minimig's for all now

When the RTL is released too, I will try and port it to my two Xilinx boards and pass them back to Dennis for his page.

Those boards are not as good as the Altera ones for this core as they do not have an SDCARD slot. The Xess one only does 512 colours too, but this can be fixed by adding three resistors I guess !

In the meantime I WILL order a DE1 for sure now.

Is there any preference on type of mouse that is needed ?

In the meantime a slightly less important thing will be happening tomorrow when the Dev boards for my MiniMorph boot loader will arrive. I will be one step closer to adding Ethernet to the Minimig.

[MiniMorph]

I have just ordered 5 Altera DE1 boards from Taiwan.

I will sell a couple of them on in the UK if there is interest. I could sell them privately or on Ebay.

I could probably do the mouse keyboard mod on the boards and I will see if I can get some y cables as well. I will need then anyway.

Good news for my boot loader too. My development boards for that arrived today. I can actually run some code now !

[MiniMorph]

I will share the code for the Minimorph Loader when it does useful things. I will be making both binary builds and the source code available.

It is some way off being useful. I am unsure how much work will be involved in modifying Tobiflex's design to be more like the Original Minimig where it communicated with the PIC. I need the SDRAM and 68000 core from Tobiflex's design but set up to talk to an external boot loader like Dennis's design.

[MiniMorph]

Great Work TobiFlex!

My 5 Altera DE1 boards arrived today

So I can try it when I get home!

[MiniMorph]

I have my DE1 board doing something now!

Thanks Tobiflex and Dennis.

I have a big problem now.

I have never used an Amiga before  :-?

I still have 4 boards fresh in their box.

[MiniMorph]

According to Tobiflex on this very thread the DE1 is 73% full with the MiniMig in it.

When the RTL is released I will find out for myself.

I will need the RTL to get it working with my Minimorph Boot Loader. The code will not be ready for a month or two however so there is no rush.

I am not quite sure how much the DE1 boards have cost me yet. I will try and get round to working it out. I have also got the mouse/ keyboard splitter cables on order I should have them by the end of the week.

I have an MSX core on my PC for the DE1 too (Not mine you understand). A certain guy from Australia claims to have quite a few cores for the DE1.

I have MikeJ's VIC20 running on one of my Xilinx boards so a port to the DE1 is on the cards. I will have to search out a C64 too.

All the best.