hi
i am toying with system09 from OpenCores, it fits perfectly on spartan3 500K gates but is uses the 70% resources on spartan 3e 200K gates so i can't imagine it could fit into my poor 100K gates device.

I know that 6809's state machine and control logic, unlike many processors of the day, was mostly implemented using a large PLA and asynchronous random logic (a trait of early designs and, partly, of RISC) rather than microcoded, i wander if there is a microcoded version of such a chip, because i have hot 4 Bram on my spartan 3e 100 so i could think they could help to have a 6809 microcoded into my device.

I mean: having the micro code ROM into b16 BRAM may save a lot of LUTs =D

what do you think ? have you seen such a microcoded 6809 soft core around ? is it a bad idea ?

any suggestions are welcome =)

Hi!
In a series of experiments Electric_Eye synthesised as many as 10 different 6502 cores:
viewtopic.php?f=10&t=1673
showing a wide variation in how compact they come out. I'm not aware of any 6809 cores, but the same principle will apply: the core you have probably isn't as small as it might be. It would probably take a bit of work to recode one of the 6502 cores as a 6809, but the architectures are not so very different.

(It's notable that the 6809 core you have is, I think, 20,000 lines of HDL, whereas Arlet's 6502 core is only 1500 lines!)

so no way ?

What I think that comparison says is that the (only) 6809 core we have is not written as compactly as it could be - the 6809 surely doesn't need more than 2 or 3 times the complexity of the 6502.
But, we still need to find or write a more compact core.
Cheers
Ed