Help emulating LINE interrupts
Posted: Fri, 16.02.2018 19:21:37
Hi
I'm trying to emulate LINE interrupts on ZEsarUX. According to the documentation, line interrupt is enabled when bit 1 of register 2AH set. It seems to be correct, as I tried the Chess demo and it seems it uses it
Then I see other three registers:
HSINT
VSINTL
VSINTH
I guess that an interrupt is fired when the scanline is at the position (VSINTL+VSINTH(bit0)) and t-states on line is HSINT. I think my guessing is right.
But, I have some questions:
-When the line interrupt is fired, do I have to call it like a IM2 interrupt? And, do I have to notify somewhere about this interrupt? I read something (translated to russian) like:
byte D [7: 0] in SD on cycle~ IORQ || ~ M1.
- $ FF - personal,
- $ FD - line,
- $ FB - DMA.
??
-Are these interrupts called even if the cpu has interrupts disabled? (DI)
I tried with the chess demo, the image is not seen well (only top half of the screen), and when I fire the interrupt, only the music goes faster, the display is wrong
Thanks
Cesar
I'm trying to emulate LINE interrupts on ZEsarUX. According to the documentation, line interrupt is enabled when bit 1 of register 2AH set. It seems to be correct, as I tried the Chess demo and it seems it uses it
Then I see other three registers:
HSINT
VSINTL
VSINTH
I guess that an interrupt is fired when the scanline is at the position (VSINTL+VSINTH(bit0)) and t-states on line is HSINT. I think my guessing is right.
But, I have some questions:
-When the line interrupt is fired, do I have to call it like a IM2 interrupt? And, do I have to notify somewhere about this interrupt? I read something (translated to russian) like:
byte D [7: 0] in SD on cycle~ IORQ || ~ M1.
- $ FF - personal,
- $ FD - line,
- $ FB - DMA.
??
-Are these interrupts called even if the cpu has interrupts disabled? (DI)
I tried with the chess demo, the image is not seen well (only top half of the screen), and when I fire the interrupt, only the music goes faster, the display is wrong
Thanks
Cesar