[comp.sys.mac.programmer] 8.24 GC Problem

wayne@helix.nih.gov (Wayne Rasband) (11/14/90)

 If I enable the  accelerator on the 8.24 GC card, and use CopyBits to 
copy from a PixMap stored on a NuBus card(Data Translation QuickCapture 
frame grabber), the result looks like garbage. I am using a PixMap base 
address in the form $Fssxxxxx, where s is the slot number($9-$E). 
According to "Designing Cards and Drivers", addresses in this form are 
valid in both 24-bit and 32-bit addressing modes. I'm I doing something 
wrong, or is this a known bug?

Thanks in advance,

-wayne rasband

wayne@helix.nih.gov (Wayne Rasband) (11/16/90)

Thanks to a tip from reinoud@duteca.tudelft.nl, I have fixed the problem I 
was having doing "live video" in NIH Image when the 8.24 GC accelerator is 
enabled. It turns out that the secret to getting the  QuickDraw/QC to work 
with PixMaps on frame grabber cards is in Tech Note 275. It tells about a 
new pmVersion (baseAddr32 =4) for 32 bit (NuBus) baseAddresses, and 
explicitly mentions video grabbers! The QuickDraw/GC must require this 
information to fetch data from NuBus PixMaps.

--wayne