Differences

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--- making_full_use_of_memory_ports [2020/10/12 10:48] – [REP0 and REP1] laubzega
+++ making_full_use_of_memory_ports [2020/10/13 19:56] – [Copying data in local RAM] laubzega
@@ Line 120: / Line 120: @@
 While this approach is faster than copying data in C64 base memory (you can use the simplest addressing modes, and don't have to worry about updating the source and destination addresses), it still is far below theoretical throughput of the ports - even with unrolled loops the best we can do is around 8 cycles per byte (<125KB/s).
-As you might have already suspected, we can side-step the CPU entirely, and copy data directly using ports' DMA channels. This mode is activated by activating ''CTRL_PORT_COPY_MODE'' in ''CONTROL'' register. Here is the fast way to copy 256-bytes:
+As you might have already suspected, we can side-step the CPU entirely, and copy data directly using ports' DMA channels. This mode is activated by setting ''CTRL_PORT_COPY_MODE'' in ''CONTROL'' register. Here is the fast way to copy 256-bytes:
 <code>
@@ Line 140: / Line 140: @@
         LDA #0           ; As previously, "0" means "256".
-        STA VREG_REP1    ; Write to REP1 kick-offs hardware copy.
+        STA VREG_REP1    ; Write to REP1 kicks off hardware copy.
 </code>
@@ Line 161: / Line 161: @@
 Final two comments:
   - Because of how DMA channels are allocated within a cycle, accelerated copying is only possible  from PORT0 to PORT1, not the other way around
-  - ''STEP0'' and ''STEP1'' can naturally differ, enabling you to reorganize your data as you copy it: change order, insert gaps, etc.
+  - ''STEP0'' and ''STEP1'' can naturally be different from each other, enabling you to reorganize your data as you copy it: change order, insert gaps, etc.
 For comprehensive example demonstrating use of all these features, please see [[https://github.com/madhackerslab/beamracer-examples/blob/master/asm/demo_hirestext.s|demo_hirestext.s]].