[Coco] Coco Digest, Vol 48, Issue 53

[Paul Fitch]

> Message: 14
> Date: Mon, 30 Jul 2007 20:49:04 -0400
> From: Robert Gault <robert.gault at worldnet.att.net>
> Subject: Re: [Coco] Nitros9 high speed mode
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Message-ID: <46AE8700.40506 at worldnet.att.net>
> Content-Type: text/plain; charset=us-ascii; format=flowed
> 
> Joel Ewy wrote:
> > I think this thread is suffering from insufficient specificity.  :) 
>  ><snip>
> 
> Boy did you hit the nail on the head with that comment!
> 
> The module that turns on the 2MHz, and native modes in Level2 6309 is 
> Rel. There is no reason to go to 1MHz or emulation mode and 
> these mode 
> should not be changed without a VERY good reason.
> 
> Since the system does not expect the above to change, I don't think 
> there is any test made for these changes. There is a shadow 
> register on 
> the system direct page, D.MDREG, which will tell you whether 
> you are in 
> native mode. If you have not studied the OS-9 defs, and already 
> understand the direct page content, you should not consider 
> any changes.
> 
> It is possible for user programs to revert to 1MHz and emulation mode 
> with one important caveat. You can't let the system regain 
> control until 
> you return to 2MHz and native mode. That means all IRQs 
> should be turned 
> off, vectors saved, vectors redirected, speed and mode 
> changed, and IRQs 
> restarted. This completely defeats the point of using OS-9. 
> You might as 
> well write a stand-alone ml program to run from Disk Basic.
> 
> 

Ok, now I'm more informed.  And I thank you all for your thoughts.

First, I was never aware (that I can remember) that OS9 Lvl2 ran at "high"
speed natively.  I remember the Poke that was used under disk basic, but
didn't make the connection.  The last time I had a real coco keyboard under
my fingers was in 1994<G>.

I'm running the 6309 Nitros v030206 under emulation using MESS104.  When
Mess starts it reports the emulated Coco3's speed as .89 mhz.  So that's the
only actual number I've seen.  I'm wondering if the emulated Nitros9 is
actually running in high speed tho, because how would MESS know to allow it?

Mess has a "throttle" command, that clearly speeds up long dsaves and other
actions, but the keybounce (SSSSPPPPPPEEEEEEELLLLLLEEEDDDDDDDD
KKKKKEEEEYYYYYBOUUUUNNCCCCCCE) makes it impossible to actually interact with
OS9 when the throttle is turned off.  Now I know the speed difference I see
with Throttle turned off isn't the same thing as the .89 vs 1.78 mhz Coco
and Nitros speeds, so.

>From what you all are saying, on a REAL coco, with a 6309, Nitros9 6309 runs
in Native mode at 1.78 mhz.

I suspect that under emulation, it stays at a simulated .89 mhz, no matter
what Nitros thinks.  

Personally speaking, I like MESS.  I just wish it were optimized for the
COCOs, with all the other stuff yanked out.  Then Nitros could be altered
with an emulated environment in mind, and we could see some real speed
increases.  

Even without that, if they just fixed the interface and virtual disk bugs,
I'd be happy.  But again, with 100's of systems supported by the one
emulator, fixes are not going to come as fast as I'd like.