[Coco] 6309 running in a Coco 1

[Bill Pierce]

The Nitros9 sources in the current repo can be built for Coco 1-2-2b-deluxe as well as all the dragon models with 6309 code. All that would have to be done is the make files would have to be setup for the builds. The Coco 3 makefiles could be used as an example of what needs to be added to create the 6309 builds.

The problems I see with this is that you couldn't run in 6309 native mode on Coco 1&2. (Dragons too I think). Since the 6309 native mode runs at double clock speed, the Coco 1&2 would lose video just as it does when using the poke65495,0 & poke65497,0 in Basic. It's the very reason the double clock wasn't used by software on the 6809 back in the 80s. The VDG chip can not take the speedup. Possibly the SAM as well (???). On the Coco 1, the bitbanger port cannot use this mode as well. That's why there's no "Turbo mode" DW4 drivers for Coco 1. The Coco 1 had a flawed serial output and maxes at 38,400.

The nitros9 sources would have to be set to "emulated" mode instead of "native" mode so that the 6309 opcodes could be used at normal speed. You will lose the double speed but still gain the 6309 opcode speed up. Only a few modules in the nitros9 sources actually gain any speed from the 6309 opcodes. The real gain in nitros9 L2 Coco 3 with 6309 is from the double clock speed which made most 6809 code faster as well. You will lose this on a Coco 1&2

In the end... I don't think what little speed you would get from the 6309 opcode would matter that much. Maybe in graphics manipulation, but anyone else running the software would have to have a 6309 to see it as well.

Bill Pierce
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-----Original Message-----
From: Harry Hurst <hhos at st-tel.net>
To: coco <coco at maltedmedia.com>
Sent: Thu, Jan 2, 2014 10:38 pm
Subject: Re: [Coco] 6309 running in a Coco 1



> My question is this.  Has anyone updated a L1 version of NitrOS-9 or OS-9
> for that matter to a 6309 version yet or should I begin to attempt this?
> All the L2 code has been updated to 6309, so side by side comparisons of
all
> like modules should be doable making the appropriate changes of course.
> Except for the modules with the MMU code in NitrOS-9 L2 would a
> replacement of 6809 modules that have nothing to do with the MMU logic
>for the 6309 versions of those same modules be possible to end up with
a >6309 version of NitrOS-9 L1?

I had been under the impression that NitrOS9 could be assembled as 6309. I
looked at a couple of module source files I have on my computer. The
krn.asm is the only one I checked that had conditional assembly structures
in it, but the condition was "IFNE H6309", which would evaluate to true if
H6309 was anything but 0.

These sources that I looked at are pretty old, and there isn't a lot of
6309 only code in the one file with the conditionals, but there may very
well have been a great deal done since then. It could all be done already!

>
> Has anyone else been thinking of doing this yet?  Surely I'm not the only
> one.
>

You're not the only one. I thought about it but I like my CoCo3's so much
better that I didn't try very hard, if at all. :) Still, I have been
trying to exercise my brain a litte more, so...maybe...? I'll think about
at the very least.

> I have upgraded the 68HC11 highlighter module for the programmer's ConTEXT
> editor for Windows to be 6809/6309 compatible plus I added all the OS9
> pseudo-op code and assembler directives that I know of or found in the
> Boot_rom.asm file I used as an example file to check my work, so now all
> the appropriate things get highlighted properly.

What is this? A 6809/6309 highlighter for a text editor? That would be
nice to have. My editors all identify the 6809 sources as 6502 assembly
language and apply that, which isn't bad, but not terribly useful either.
I only use Linux, though. I don't imagine that would work for me. How do
you edit something like that? I might try to do something like that, if it
hasn't already been done.

I'll let you know privately if I am interested in the Level 1 6309
project. First, I think I'll see if I can find the latest Level 1 sources.
If they have a lot of 6309 conditionals in them now it may be that you
will only have to start assembling modules to get what you want.

Regards,
HH


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