> On Wed, 9 Aug 1995 13:07:00 +0200, Frode Tenneboe said: > > I'm sure. It's 228 on all 128K models (I'm a bit unsure about the original > > Sinclair 128K, though). However, there is also a difference between > > the +2 and the +2A/+3 being that one is 'in synch' on the first cycle > > of a four cycle cycle, while the other is on the second. > > Ah but which is which? :-)
I knew that ..once. :) I'm 90% sure it was the +3 that was on the first, while the +2 was on the second. It's all in the code for TNT....:) > > 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? > > > > This information should be written in the reference section in the speccy > > > manual (because it is relevant to the contended memory). > > > It is? > > Yes, it is relevant because the memory is only contended while the screen is > being drawn. The +3 manual specifically says that this happens for 128 out > of every 228 cycles in each scan line, and for 192 out of 311 scan lines. Yes. Then you meant "...should _have_ been written..."? :) 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.... > > imc > -Frode
