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Old 22 June 2017, 12:35   #163
grond
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Join Date: Jun 2015
Location: Germany
Posts: 364
Quote:
Originally Posted by demolition View Post
SAGA and PAMELA works in parallel with the original ECS and PAULA so they should still run normally, at least that is how I understand it. In the videos they show HDMI video being identical to RGB video on separate screens so clearly they are working in parallel.
This video was done during the early development stages and writes to chipmem were mirrored to Vampire fastmem. This meant that there was still output coming from the RGB but also that the overall processing speed was tied down to the original chipmem bus. Even though this slow speed might in theory have been acceptible to some, it just cannot work for a full-featured secondary implementation because the SAGA blitter also would have had to write a copy through the Amiga bus in order to update the RGB output. However, only the part of the Amiga bus bandwidth visible to the CPU could be used for this mirroring and this part is less than the combined bandwidths of blitter, CPU and DMA as seen from the chipmem. This means that the chipset implementation would have been significantly slower than the original making games and stuff unplayable (especially for higher colourdepths).
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