[Coco] Embedded coco

[jdaggett at gate.net]

jim

I found the 68B09E on Ebay. Three tubes for,  27 parts all 1999 date codes for $35 
shipped. The 68B21's also on Ebay a tube of 9 of them for $15 plus shipping. The 
20v10 and the 16V8's I also got on Ebay at slightly under half of what a new part 
costs.

As for a 6809 in a FPGA there are two opensource versions out there. One is a 
strict behavioral model and does not synthesize very well into a Xilinx Part. It takes 
up 95% of a SpartanII/IIe 200K gate part. There is another core that has other part 
to it as a SOC that syntesizes into a Spartan II/IIe 300K gate. If you strip out just the 
6809 cpu core that John Kent has done it synthesizes into Xilinx 200K gate Spartan 
II/IIe and occupies 90% of that. 

I have looked ot the VHDL code of both models and and there is work that can be 
done on both to make it synthesize more efficiently. The John Kent code runs only 
at about 10MHz clock. The other I think might run at 15MHz. I have not simulated 
that or tried any of the testbenches to see if it works and at what speed.

There is a commercial 6809 software compatible core that company's name elludes 
me now. I have no idea of what they want for the core code. They offer the core 
code or they will synthesize it to what ever FPGA or ASIC you want. They clain 25 
MHz speed with 25 nS ram. 

With modern silicon it would not be impossilbe to get 40 to 80 Mhz speed in ASIC. 

As for porting OS9 to the HC12 is not that to far fetched an idea. What quickly 
comes to mind is that the HC12 does not have the U pointer register, access to the 
DP register as the 6809, and does not do the pre/post double decrement/increment 
on the pointer registers. There is the LEAx instruction and a bunch of other 
instructions that are nice.   

Just looking at the sources in an ide written for the HC11/12 it the 6809 code is not 
highlighted and therefore easy to see pnuemonics that are not the same.

The main problem in using XLATE09, which is a Motorola freeware program to 
convert 6809 code to 68K code, is that it is 95% efficient at best in converting code. 
You will have to do a lot to cleanup. It to is doable. There is no 6809 emmulation 
mode in the 68K or CPU32 core. One can write software to  emualte a 6809 on the 
68K processors. 

james
 

On 17 Dec 2003 at 16:40, jimcox at miba51.com wrote:

> James:
> 
> Given the age of a lot of these parts, how much trouble 
> have you had finding them?  Maybe a FPGA version would be 
> more of what is needed or take another chip such as the 
> HC12 and port NitrOS-9 over to it.  Someone was talking of 
> porting it over to the 68000 or at least running a 68000 
> in 6809 mode (never heard of that before the recent 
> conversation)
> 
> Jim
> 
> On Wed, 17 Dec 2003 19:36:18 -0500
>   jdaggett at gate.net wrote:
> >Gee whiz 
> >
> >Sounds like something I was thinking of for a project. I 
> >was going to start with a 
> >CoCo3 and then maybe into a striped down version. Maybe 
> >still able to run a 
> >stripped down version of OS9 in flash and a small to 
> >medium LCD display. 
> >
> >A couple of questions:
> >
> >1) what kind of ram and how much?
> >2) Which PCB layout tool you plan to use?
> >3) Will you include the current expansion port of the 
> >CoCo?
> >4) Total Ram and Rom on board? 
> >5) Any provisions for SRAM in surface mount package
> >6) Resistors and caps in Surface mount or thru hole?
> >
> >I have been accumalating parts now for about three months 
> >and looking at some 
> >software. 
> >
> >james
> >
> >On 17 Dec 2003 at 15:06, peak at mail.polarcomm.com wrote:
> >
> >> About using a coco mother board as an embedded 
> >>controller!
> >> How many people would be interested in a mini coco?
> >> It could/would be on a small ckt board and would have:
> >> cpu(6809)
> >> rom
> >> ram
> >> a PIA or two (address decoded to the exact same 
> >>locations as 
> >> a real coco.
> >> DAC
> >> Small PAL/PLD used as an address decoder. Both the CTS, 
> >>and 
> >> the SCS lines would also be duplicated.
> >> 
> >> WhY?
> >> Because by using the same hardware memory map for the 
> >>PIA's 
> >> and DAC would allow a much smaller controller . also a 
> >>real 
> >> cocoI or II would not have to be sacrificed to use as 
> >>the 
> >> controller. But a real coco could be used to test and 
> >>debug 
> >> software before it was placed in rom on the embed board!
> >> 
> >> If anyone is interested I will design the ckt board and 
> >>place 
> >> the design in public domain or even post it here if 
> >>allowed.
> >> Heck I may design this thing anyway just for myself. Any 
> >> takers??
> >> 
> >> Eric 
> >> 
> >> -- 
> >> Coco mailing list
> >> Coco at maltedmedia.com
> >> http://five.pairlist.net/mailman/listinfo/coco
> >
> >
> >
> >-- 
> >Coco mailing list
> >Coco at maltedmedia.com
> >http://five.pairlist.net/mailman/listinfo/coco
> 
> 
> -- 
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> Coco at maltedmedia.com
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