[Coco] Does anyone have a Level3 disk that actually boots?

[Bill Nobel]

I think you memory is right on this Curtis, I am going through IOMAN right now and I am starting to see the mapping routines.  Haven’t fully deciphered it yet, but getting there.  The Nitros9 module splits out the SCF/RBF modules into there own banks of memory, from the boot file (hence the _end modules as the markers for end of each section)

Bill Nobel

> On Nov 28, 2014, at 3:16 PM, L. Curtis Boyle <curtisboyle at sasktel.net> wrote:
> 
> From what I remember, the main difference is that there are two different 16K “mini-system RAM memory maps” for RBF and SCF. So, All the regular systems modules (and system RAM) like IOMAN, OS9p2, Windint, etc. can use up to 48K of system RAM, and then you have 16K for RBF and it’s drivers/devices, and another 16K for SCF and it’s drivers/devices. So, essentially, it allows an 80K kernal (instead of the normal 64K), which allows more process descriptors, window descriptors, path descriptors and screen descriptors, by up to 16K.
> 
> 
> L. Curtis Boyle
> curtisboyle at sasktel.net
> 
> 
> 
>> On Nov 28, 2014, at 3:08 PM, Robert Gault <robert.gault at att.net> wrote:
>> 
>> Michael Kerpan wrote:
>>> Long time lurker, wandering out of the shadows here with a simple question:
>>> what exactly does Level 3 bring to the table over and above level 2? Given
>>> that Level 2 is already making full use of the 6*09 and the Coco 3 MMU, I'm
>>> confused as to what Level 3 could possibly add.
>>> 
>>> Mike
>>> 
>> 
>> Mike,
>> 
>> Here is a quote from Alan DeKok who developed most of Level III.
>> "Level III enables you to have about 25 _different_ processes
>> running in different windows, all at the same time!  The only way that this
>> is possible on a Level II system is to strip your OS9Boot file down to almost
>> nothing.  Level III allows you to keep all of your favorite modules in your
>> OS9Boot."
>> 
>> In short, memory is handled differently from Level II and appears to be used more efficiently. Unfortunately, the source code for Level III seems to have been lost and the actual workings can't be compared with the current versions of Level II. As NitrOS-9 is more efficient than OS-9 (on which Level III is based), comparisons of Level III with current code need to be done.
>> We don't know which is better or what the difference would now be.
>> 
>> Robert
>> 
>> 
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