VASYL & access to system bus

[laubzega]

Anyway, now I have I doubt about BADLINE. 
Below what I understood so far (wihout AEC handling):

1. it doesn't wait for condition, after the beam check the VASYL will execute the next instruction
   
   
   
2. if the target raster is reached that raster line becomes a badline
   
   
   
3. Otherwise, all the other rasters between become non-badline. So, for example: VIC is on raster 100, VASYL executes BADLINE 2 => raster 100 and 101 become non-badline while raster 102 becomes a badline.
   

Now, if the execution continues with the next instruction, does it mean that VASYL remembers that it has to force a badline or a non-badline according to raster line target (as I do in the emulator) ?
Where, in this process, AEC signal is checked ?

BADLINE is actually very simple to implement:

BADLINE ARG

is equivalent to

R = PEEK($D012) ; RASTER
C = PEEK($D011) ; CR1
MOV $D011, (C & $f8) | ((R & $07) + ARG) & $07)

(I hope this mix of BASIC, C and Vasylese is not too eye-searing ).


That is, it changes VIC-II YSCROLL to a value that will cause the badline to occur after ARG rasterlines. This also means that all earlier lines (if there are any), will be non-badlines.

There is no extra waiting or anything else happening, beyond what is needed to execute a successful MOV.