[Coco] NitrOS-9 newbie needs some help

[jdaggett at gate.net]

Boise

One thing that comes to mind after reading what you posted and 
looking at the Coco3 schematics,  I wonder if the real problem is 
load capacitance and impeadance. 

The E and Q clocks from the GIME chip have a series 47 Ohm and 
a 30 pF shunt cap. This forms a low pass filter to remove some of 
the harmonic contents of the clock signals and rou nds the edges 
off. Now when you place three or four cards in the MPI and if the 
MPI does not buffer the clock lines, well  now we can have some 
issues with the load impedance on the clock signals and some 
skewing of the two to cause some timing issues. 

Four LSTTL loads will be about 500 Ohms and and another 30 to 50 
pF capacitance on the clock signals from the GIME chip. Now you 
start to get to a marginal point to where critical timing issues can be 
affected. Swapping cards generally means that you are altering the 
load impedance by plugging in a card that has a slightly higher 
impedance and thus works. 

Some cards use both the E and the Q and some on ly the E clock. 
IF you load the E clock to much and the variation between rise and 
fall times of the E and Q clock differ signifiacantly,then the CPU 
may not operate properly or certain peripheral devices will not 
either. 

It is sounding to me that the GIME chip may have a drive issue on 
the E and Q clock and that putting to many loads on the E and the 
Q clock lines is becoming a problem. 

james 

On 9 Aug 2004 at 7:56, Boisy G. Pitre wrote:

From:           	"Boisy G. Pitre" <boisy at boisypitre.com>
Subject:        	Re: [Coco] NitrOS-9 newbie needs some help
Date sent:      	Mon, 9 Aug 2004 07:56:39 -0500
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> Hello Nick,
> 
> I'm glad to see you're venturing back in the OS-9 waters.  Things have
> changed quite a bit from Tandy's OS- 9 release, and I consider
> NitrOS-9 to be a whole new ball game in some ways.  I read your post
> and saw the problems you were having.
> 
> On Aug 8, 2004, at 10:07 PM, Nickolas Marentes wrote:
> > This leads me to the present. My next idea is to try and replace the
> > RAMS in my 512K upgrade (I have a 2 x 256Mb SIMM type upgrade) with
> > another brand...if I can find some.
> >
> > Here are a few questions....
> >
> > 1) Why should NitrOS-9 be so fussy? I have NEVER had a problem with
> > my CoCo3 (A PAL unit mind you, could this be the problem?).
> 
> NitrOS-9 definitely pushes the CoCo harder than RS-DOS, there is no
> question about it.  While all of the CoCo 3s I have here will boot
> NitrOS-9, I've heard reports that some CoCo 3s will just flat out not
> boot at all.  The reasons are probably numerous, but I think it all
> boils down to timing and stability of hardware.  Some CoCo 3s, disk
> controllers and other components are less tolerant than others when it
> comes to timing.  There have been situations where, like in your case,
> swapping a disk controller made the difference between failure and
> success.  There is no easy answer here, except to say that despite
> best efforts, not all hardware is created equal.
> 
> I think NitrOS-9 Level 2 may magnify problems with CoCo 3s or hardware
> that aren't necessarily seen under Disk BASIC for the following
> reasons:
> 
>  (1) NitrOS-9 Level 2 runs the CoCo 3 at 2MHz continuously whereas
>  Disk 
> BASIC does not.  Clock speed increases means higher speed, but also
> shorter cycles.  Hardware may be just on the edge at this mode, and
> sometimes will cause random glitches.
>  (2) NitrOS-9 Level 2 also uses the MMU and GIME extensively.  It is
> constantly using MMU registers to swap memory in and out.  This hard
> banging on the GIME may bring out anomalies that aren't seen on Disk
> BASIC because, again, BASIC doesn't hit these registers very much.
>  (3) When formatting a disk, NitrOS-9 assumes double sided 40 track. 
> Disk BASIC only uses 35 tracks on one side.  So more of an "untouched"
> area of the disk is being formatted by NitrOS-9, possibly revealing
> media flaws that Disk BASIC would not have seen.
>  (4) NitrOS-9 Level 2 sees and uses all RAM.  If you have flaky memory
>  
> somewhere, changes are NitrOS-9 will hit it, and it could come at the
> worst possible moment (i.e. the RAM is allocated for code usage, and
> execution through bad RAM may cause bad results, jumps, etc)
>  (5) NitrOS-9 Level 2 is a "boot and use" OS.  Disk BASIC is a 
> "use-reset" system where you load a game or other M/L program, use it
> then reset.  Since NitrOS-9 tends to run longer without reset, there
> is the tendency for things to get hotter (especially at 2MHz mode) and
> heat can also do weird things to a computer's operating ability.
> 
> I'm not saying any of these were the cause of what you were seeing. 
> These are just my observations as to how NitrOS-9 pushes the CoCo in
> ways that BASIC does not, and therefore could reveal underlying issues
> in systems that have marginal or less than tolerant hardware.
> 
> > 2) Other than the formatting, NitrOS-9 otherwise behaved perfectly.
> > Is there a GUI available for it? I have downloaded the "Getting
> > Started with NitrOS-9" and the "NitrOS-9 Level 2 Windowing System"
> > manuals (which are very good!). It seems to me that much of the GUI
> > elements are already built in to the system. I know of MultiVue but
> > I shudder at trying to run that again.
> 
> There is Multi-Vue, but frankly I'm no fan of it either.  I can 
> understand Tandy's reasoning behind putting basic windowing elements
> (like drawing and managing windows) in system state modules like
> windint and grfdrv, but I believe that a better GUI could be built
> mostly from a user state program.  Nick, I believe this is something
> that you could probably do rather well, and I'm sure your talents
> would be welcome in this department.
> 
> > 3) Are there additional manuals available? I read in the "Getting
> > Started" manual about a "NitrOS-9 Commands Reference" and a
> > "Technical Reference" manual.
> 
> Those are being worked on.  They are massive manuals, and I'm going
> through and converting existing HTML into Word documents where they
> are much easier to edit and manage.  I'm in the Technical Reference
> but haven't gotten very far.  Bob Emery is handling the Commands
> Reference. 
>   These documents are critical to learning NitrOS-9 and how to get
> around in it.
> 
> > 4) Have there been any new (well, newer than 1992) applications
> > written for OS-9/NitrOS-9?
> 
> I'm sure there have been, though I can't think of any big ones at the
> moment.
> 
> > Boisy and everyone else involved have done a marvalous job with
> > NitrOS-9. I guess I'm looking at it all from a newbie/outsider
> > perspective. NitrOS-9 could do with a bit of "glitz". This would
> > come in the form of a GUI front end and updated applications. Sure,
> > I'd like to develop for it but it's taken me over 15 years to get
> > this far. I hate having to battle with the OS. The OS should be a
> > tool towards creating other applications. So far, OS-9 has been like
> > a bent screwdriver with me spending more time trying to get the
> > bends out that actually fixing the job at hand.
> 
> All of the work up to this point has been getting the operating system
> at a level of usability so that good applications can be written.  I
> think V03.02.04 comes very close to that.  So far, there have been no
> complaints and everyone that has used it has praised it.  I think this
> latest release is the best so far.
> 
> Again, the glitz comes from guys like you.  I'm giving you the stable
> base from which you can launch your applications.  Now we just need to
> see those applications.
> 
> > NitrOS-9 certainly has fixed many of the problems of the original
> > CoCo3 OS-9.
> >
> > I'me determined to get it right this time. I've spent a week on it
> > so far. I'll give it another week...before giving up again.
> >
> 
> I think that with some patience and help from us, you will be able to
> get a usable system put together.
> 
> Your use of NitrOS-9 brings up an issue that I have ignored up to this
> point.  I don't think anyone has needed the 50Hz clock, since everyone
> using it seems to be in the US.  There are two modules that have to
> change to accommodate 50Hz users like yourself.  I will work to put
> together a distribution especially for you that addresses the 50Hz
> issue, and I will start putting those disk images into the project
> starting with the next release (V03.02.05).  I don't plan on releasing
> again for some time, so I'll make the disk images and email them to
> you.
> 
> Robert Gault can refresh my memory here.  rel and clock2_soft are the
> candidates, correct Robert?
> 
> 
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