From: Jon M. Taylor <taylorj@ecs.csus.edu>
  To  : ggi-develop@eskimo.com
  Date: Sun, 30 Aug 1998 15:23:11 -0700 (PDT)

Re: Virge lock ups

On Sun, 30 Aug 1998, Ray Glendenning wrote:

> On Sun, 30 Aug 1998, Jon M. Taylor wrote:
> 
> > * Horizontal pixel clocks need to be doubled for 15/16bpp modes to work. 
> > They are not, so those modes don't work right (or at all in some
> > resolutions).  That is why you get out-of-range timings for those modes -
> > the slow pixel clock effectively doubles the vertical refresh rate.  When
> > I do get in-range 15/16bpp modes, they have vert refresh rates of like
> > 140Hz(!) and I can only see them because I have a nice 17" monitor. 
> > 
> 
> Yeah, I tried to fix this last year *8-)

	Me too.  It should just be a simple matter of doubling the clock
rate before feeding it to the hardware - no modifications to the clock
driver etc should be necessary.  The mode timing doesn't change, just the
effective pixel clock value.  But I could never figure out how to do it
right |-<. 

> > * The extended (8514-type) acceleration registers are never set in the
> > chipset driver and there's no Trioxx or Virge accel drivers yet.  So, no
> > accelerations are present.
> > 
> 
> *8-( 

	It's not as bad as all that.  There is a working Vision96x accel
driver, and the differences should be quite minimal as far as the basic
8514/A setup code and drawing ops.  What is more missing is the
Trio/Virge-specific accel ops.  Some are the same as Vision96x (clipping),
some are just a little different (blits, hlines), some are quite different
(lines, areafills) and some are completely new (Trio short-stroke lines,
Virge triangles, STREAMS for both).  

	Getting it all working 100% will be a decent bit of work.  I'd be
willing to help once the foundations of the drivers are working, and of
course I will be available to offer advice and the benefit (such as it is)
of my Trio coding experience, but I will not go near the foundations again
for love nor money |-<. 
 
> > 	Lots of work needs to be done on these drivers.  But I have been
> > fighting with the Trio driver off and on for two years now and I have
> > gotten to the point where I get nauseous just thinking about working on
> > them again.  The buggy brain-deadness of that hardware family is nothing
> > short of monumental.  If anyone out there would like to step forward and
> > replace me as the official Trio driver maintainer, I would welcome it
> > greatly.
> > 
> 
> I would take over at least to collect patches as I'm still learning
> myself, 

	You learn by doing in this business.  Especially with Trios |->. 

> but if noone else wants the job, I'm here.

	There doesn't actually need to be one official maintainer, just
one or more people willing to hack, patch, etc.

Jon

---
'Cloning and the reprogramming of DNA is the first serious step in 
becoming one with God.'
	- Scientist G. Richard Seed