EASy68K Circuit
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Author:  Magnus [ Wed Sep 27, 2006 4:50 pm ]
Post subject:  EASy68K Circuit

A first post here,

My name is Magnus Wedmark and have used EASy68K as a reference-bench for a FPGA-project I'm into as a hobby. EASy68K is a fantastic piece of software for lab-use and to learn the inner details in the 68k.

The project is about creating a minimal 68K-compatible IP-core for use in FPGA-projects. It is not an open project today, but it might be in the future if I get the complete 68k-opcode implemented. The reason to choose the 68K was that I just love it's assember opcode setup and I've done so since owning an Atari ST earlier! And also that the 68k-IP I've seen floating around seam to be BIG in terms of FPGA-resource needs.

The reason for me to post this here is to see if there are somebody interested in having a complete/partly-complete EASy68K-IP core? Wouldn't it be nice to have a hardware EASy68K-chip to run all programs on?

I'm using the original Xilinx Spartan-3 Starter Kit that includes a Spartan-3 200k FPGA. I read about the MECB project here in another discussion and I'm not sure if we collide?
I like to ask if anyone else have had the same idea as me or is it an orignal? Somebody interested? Projects already started?

Best Regards

Author:  leeloothedolphin [ Wed Oct 17, 2007 10:16 am ]
Post subject: 

Hi, is your project still alive? I'm thinking of implementing 68k in FPGA.

Best regards,

Author:  Magnus [ Sun Oct 21, 2007 11:24 am ]
Post subject: 

Hello, Maja

Good to find another FPGA+68K hacker! What is you interest in such a project? EASy68K-HW or the core for use in other projects?

Remember that 68K is not your best first try at a core in VHDL/verilog. It was not developed this way. Both MIPS and ARM would probably be better more useful choices, thus x86 would be harder! :-) But if you are, like me, not in it for simpleness or usefulness then the 68K is just a beautiful piece of nostalgic hardware. OK enough of disclaiming...

Depending on your definition of active, the project is at least not dead. It was however almost a year since I last visited it (2006-11). I check back here once in a while to see how EASy68K follow on and if there are more people interested in this HW spin-off. This far the reading of the thread has been high but the posting has been low and I'm not sure why! :-)

Today this is not my main hobby-project but I'm still committed to finish it to get full or near full coverage of all 68k-op codes and then release it for others to play with. I have not decided if I'm going to aim for a drop-in replacement of a real MC68000 or just the op-code-execution unit... probably the ladder because cycle-accurate operation seem hard the way I chosen to implement it. There are still unanswered matters when it comes to the layout of my implementation. Is it really are possible to pull it off? I've chosen a path that make it Xilinx-only (Xilinx tools & hardware) to begin with but there is a way to broaden the image later on in the project if that would be someone's wish.

Todays status for it is approx:
- >30% of op-codes implemented, due to reusable parts maybe 50% done
- Handles B,W,L word sizes today
- 10 of 14 addressing-mode implemented
- When doing a quick overview it seem to resemble a <1Mhz 68K today
- It takes <10% of a 200K today

The first achievement will be to get a "Sierpinsky Triangle" program going that works in EASy68K, a simple fractal algorithm.

If someone is interested in more details than this, please mail me magnus(replace_this_with_at)wedmark.se and we'll take the off-topic details in a mail so we not clutter this list with even more details.

Of course I've already done a scan of which other open 68K-implementations there are out there floating around and only found two:

- SUSKA - a near complete Atari STE IP-core inc. a near complete 68K-core. The code is released now and then, it's big so you need to big FPGA to try it. Wolfgangs work is fantastic!

- There is a 68K core at opencores.org called - it is not finished but maybe it can be used as a start.. you can't find it when searching the site so just though I'd tip you off.

Anyone know of other 68K open-source IP's?

None if these cores have a goal similar to mine. The goal of my project is to get an absolute minimum core at the cost of performance which will be low in a first revision.

Depending on your goal, just for fun project or a school-work, maybe you have the possibility to learn from these.

OT warning:
And for an off-topic brief view of what I'm doing today visit:

The thing called AE - Arcade Extender, is the hardware I've developed and are playing with. Together with my friends IP-core ULC (Ultimate Little Console) they form a gaming/demo platform. The specs and JAVA-simulator for ULC can be downloaded by following the descriptions from my webpage.

Right now I'm aiming for a C-compiler for it. The compiler will by built from scratch using the "COCO/R for C#" tools.

See ya!

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