68k interrupts: Difference between revisions
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Interrupts need to be acknowledged by writing to register $3C000C (REG_IRQACK). | Interrupts need to be acknowledged by writing to register $3C000C (REG_IRQACK). | ||
bit2: Ack VBlank | *bit2: Ack VBlank | ||
bit1: Ack RLI | *bit1: Ack RLI | ||
bit0: Ack level 3 | *bit0: Ack level 3 | ||
<pre> | |||
move #$0007,REG_IRQACK ; Acknowledges all interrupts | |||
</pre> | |||
Bits 8~10 of the SR register are used to mask them. $2000 enables them all, $2700 disables them. | Bits 8~10 of the SR register are used to mask them. $2000 enables them all, $2700 disables them. | ||
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== Raster Line Interrupt == | == Raster Line Interrupt == | ||
The RLI interrupt's behavior can be programmed through memory mapped registers. It's made to occur at (the start/end ? of) specific horizontal lines of the video output. See the Sammy logo at the start of [[Viewpoint]] for an example of its use. [[ | The RLI interrupt's behavior can be programmed through memory mapped registers. It's made to occur at (the start/end ? of) specific horizontal lines of the video output. See the Sammy logo at the start of [[Viewpoint]] for an example of its use. [[Sengoku 3]] and [[Neo Turf Masters]] are also known to rely on them to do [[scanline effets]]. | ||
== AES/MVS interrupts == | == AES/MVS interrupts == | ||
VBlank: 0 | *VBlank: 0 | ||
RLI: 1 | *RLI: 1 | ||
*Pending at startup ?: 2 | |||
== CD interrupts == | == CD interrupts == | ||
VBlank: 1 | *VBlank: 1 | ||
RLI: 0 | *RLI: 0 | ||
[[Category:CPUs]] | [[Category:CPUs]] | ||
[[Category:Code]] | [[Category:Code]] | ||
Revision as of 08:29, 23 February 2011
There are 3 interrupt levels on the AES and MVS. Only 2 on the CD hardware.
Interrupts need to be acknowledged by writing to register $3C000C (REG_IRQACK).
- bit2: Ack VBlank
- bit1: Ack RLI
- bit0: Ack level 3
move #$0007,REG_IRQACK ; Acknowledges all interrupts
Bits 8~10 of the SR register are used to mask them. $2000 enables them all, $2700 disables them.
Vertical Blank Interrupt
VBlank interrupt is almost always used. It occurs everytime a new frame is traced (~60Hz).
Raster Line Interrupt
The RLI interrupt's behavior can be programmed through memory mapped registers. It's made to occur at (the start/end ? of) specific horizontal lines of the video output. See the Sammy logo at the start of Viewpoint for an example of its use. Sengoku 3 and Neo Turf Masters are also known to rely on them to do scanline effets.
AES/MVS interrupts
- VBlank: 0
- RLI: 1
- Pending at startup ?: 2
CD interrupts
- VBlank: 1
- RLI: 0