« on: November 19, 2009, 09:34:06 PM »
6 bitplane gfx costs you half CPU (or SCSI DMA) bandwidth on chip RAM during bitplane DMA. Since you're using no overscan, you can make up for part of the bandwidth loss during horizontal and vertical blanking.
You've got 225 DMA slots in each line, 312 lines/PAL frame. From the 225 cycles, the CPU can potentially use 112 (113?), 40 are lost to gfx, leaving 72. 72*256 + 112*56 = 24704 cycles per frame
16 bit chip RAM allows you to write 49408 bytes per frame, the A3000's 32 bit chip RAM would double that to 98816 bytes. Running 25 fps means you've got two frames for a full refresh (61440 bytes), so it shouldn't really be a big problem with optimized code, possibly even with a chip RAM only system!
Doesn't all that assume you are sending the entire screen data?
Can't you just send the changed data across?
Or would that take more CPU to figure out that to transfer?
desiv
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