[comp.graphics] "NTSC" framebuffer on MIPS

steve@cs.UAlberta.CA (Steve Sutphen) (06/05/90)

Some where in our multitude of computers I need to put a "dumb" frame
buffer.  The requirements for this are:
	1) 24 bit planes (or greater)
	2) NTSC timing compatibility (for a VAS-V VTR controller)
	3) 8-bit frame grab (from a B&W video camera)
	4) square pixels (if possible)

I could live with either 512x512 (with some missing lines to fit in a NTSC
frame) or 640x480.  I do not want "high resolution", or any particular
smarts.  This board is going to be used to digitize the odd video frame,
and for generating output that will be hooked to:
	1) standard TV monitor
	2) Matrix 4007 hard copy camera (RS170 - RGB&synch)
	3) VAS-V VTR controller and Sony VTR (with a Lyon Lamb RGB to NTSC
	   encoder).

I assume that the user's will be able to generate the "bits" by various
means.  

I have contemplated a few solutions to the problem:
	1) Buy a add on board for a Sun.  This has a couple of problems:
	   most of our Sun's don't have VME backplanes or S-Bus; VME is
	   expensive.
	2) Buy a standalone unit: too expensive, especially as I view this
	   as a network (Ethernet) resource.
	3) buy a PC-AT card and put in our MIPS M/120 (we have one slot 
	   that is empty).
This last solution is what I am now investigating (although I am open to
other suggestions).  I have not looked into the AT-Bus driver that will
be needed on the MIPS end, but it seems that this will work in theory (if
anyone has contrary evidence I would like to hear it).  The boards I am 
currently investigating are:
	1) Data Translation DT2871-60Hz
	2) TrueVision board TARGA-24
	3) RedLake SPECTRUM (I have a data sheet but it isn't clear if it
	   will do the 24-bit ouput, it seems oriented to PC graphics).
	4) New Media Graphics (once again it isn't clear if this will do 
	   what I want).

I am open to suggestions of other boards that I may have missed.  I looked
at the Matrox, but it takes 2-slots and I only have one.

So, what I am asking (I think) is:
	1) is this a reasonable solution?
	2) are there better solutions (unfortunately I don't have much
	   money to throw at the problem).
	3) has anyone had any experience putting a device like this (a
	   1 MByte address space) on a MIPS Machine?
	4) are there better boards?

I am willing to do a little research to track this down, so pointers are
welcome.  
As this is rather specific mail would be more appropriate than posting.  I
will summarize if warranted.
	steve@cs.ualberta.ca