Testing monitor memory

[David Brown]

We've got a 3/80 who's video memory appears to be a little wacky.  There
are white vertical lines running the length of the screen, at a uniform
distance from each other.  It appears that a video ram chip is blown.

My question: is there some way to test the video memory?  Sundiag/Sysdiag
don't have such tests (that I can find).  If not, is there a way to figure
out which of the memory chips is bad?

Sun 3/80
17" mono monitor
SunOS 4.0.3


Thanks,
  David Brown
  david at pirates.uucp
  uunet!pirates!david