> On Wed, 9 Aug 1995 13:41:12 +0200, Frode Tenneboe said: > > > Do you happen to know what the relationship is between the interrupts and > > > the > > > TV scan? > > > You mean which one comes first and how much? > > Yes. By experiment I seem to have found that on the +3 the scan line reaches > the start of the screen 14367 cycles after the interrupt is generated.
It was many moons ago since I messed around with that. Your figure seems accurate, in which case it's the +3 that's on the second cycle of a four cycle cycle. Then my guess is that the 48K is at 14112 cycles. > > > Yes. Then you meant "...should _have_ been written..."? :) > > I don't know whether it is or not. Do you mean that it isn't? It's not. For the 48K. > > > Are you sure about the 311 lines btw? I once drove pretty close to th limit > > of a frame, and I'm pretty sure that was more than 311 * 228 cycles.... > > Yes, very sure. I wrote a timing program which displays a striped border > without using the HALT instruction inside the loop. This allows me to > mess around with the timing and find out exactly how long the delay was > by looking at the position of the pattern. You can have a snapshot of > it if you like. :-) OK! I'll believe you if you can provide proof that you are competent enough to count that high. :) > > The reason for all this is that I have implemented the stripey border effect > in xz80 and at the moment it mimics the +3 precisely, but I don't have 48K > speccy info. The demo TNT should be a nice test. It's on nvg. :) > > imc > -Frode
