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vasyl_interrupts_and_vasyl_cpu_coordination [2020/10/07 02:44] – [Setting up VASYL interrupts] silverdrvasyl_interrupts_and_vasyl_cpu_coordination [2021/04/15 12:04] (current) – [VASYL interrupts and VASYL/CPU coordination] laubzega
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 While BeamRacer makes it easy to offload many graphics-related operations to VASYL, there are situations where some precisely-timed assistance from the main CPU may be needed. These can be chiefly grouped into three categories: While BeamRacer makes it easy to offload many graphics-related operations to VASYL, there are situations where some precisely-timed assistance from the main CPU may be needed. These can be chiefly grouped into three categories:
  
-  * Write to an address inaccessible to VASYL.+  * Writing to an address inaccessible to VASYL.
   * Performing computations that 6510 is better suited to.   * Performing computations that 6510 is better suited to.
   * Making sure that CPU operations happen in a specific region of the video frame, to avoid clashes over resources shared with VASYL.   * Making sure that CPU operations happen in a specific region of the video frame, to avoid clashes over resources shared with VASYL.
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 === Non-VIC writes === === Non-VIC writes ===
  
-**MOV** and **XFER** display list instructions do an excellent job of fast, precise writes to VIC-II registers. However, there are locations in C64 memory space that influence video output, and yet are beyond VASYL's reach - a canonical example here is VIC bank switching in register ''$dd00'', but it could also be just-in-time Color RAM or video matrix updates.+**MOV** and **XFER** display list instructions do an excellent job of fast, precise writes to VIC-II registers. However, there are locations in C64 memory space that influence video output, and yet are beyond VASYL's reach - a canonical example here is VIC bank switching in ''CI2PRA'' register at ''$dd00'', but it could also be just-in-time Color RAM or video matrix updates.
  
  
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         STA $315         STA $315
 </code> </code>
-  * The interrupt needs to be enabled by setting bit 4 in the ''IRQMASK'' register at $d01a (the same register that stores bits controlling VIC's interrupts),+  * The interrupt needs to be enabled by setting bit 4 in the ''IRQMASK'' register at ''$d01a'' (the same register that stores bits controlling VIC's interrupts),
  
 <code [enable_line_numbers="false"]> <code [enable_line_numbers="false"]>
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         IRQ         ; trigger another interrupt, this time at the beginning of the line         IRQ         ; trigger another interrupt, this time at the beginning of the line
 </code> </code>
-  * In your interrupt handler, you need to make sure that VASYL IRQ is acknowledged by setting bit 4 of register ''$d019'', or the interrupt will be retriggered as soon as the handler finishes executing.+  * In your interrupt handler, you need to make sure that VASYL IRQ is acknowledged by setting bit 4 of ''VICIRQ'' register at ''$d019'', or the interrupt will be retriggered as soon as the handler finishes executing.
  
 <code [enable_line_numbers="false"]> <code [enable_line_numbers="false"]>
 + ; We assume here that no VIC interrupts are enabled and
 + ; VASYL is the only possible video related IRQ source
  LDA #$10  LDA #$10
         STA $d019         STA $d019
vasyl_interrupts_and_vasyl_cpu_coordination.1602063848.txt.gz · Last modified: 2020/10/07 02:44 by silverdr