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Old 08 November 2010, 20:12   #317
Join Date: Jun 2010
Location: out in the wild
Posts: 1,126
Originally Posted by frank_b View Post
Nice! Thanks. Btw any idea what the burst speed is on the fastest 030 blizzard?
They probably do 4-2-2-2. You can't do X-1-1-1 with normal D-Ram. I make excessive use of SD-Ram features here.

Originally Posted by frank_b View Post
I saw some really odd results with an aligned move.l copy on my 030 board.
Sequential copy was slower with data burst on.
There's two things that may cause a burst to be slower:

1. you start it when it doesn't make sense (at the end of a cache line)
2. you run it all the way through, 4 longwords, "no matter what".

My ACA cards will only start a burst if it's NOT at the end of a cache line, and they stop a burst if the end of a cache line is reached. Call it a "dynamic burst", because it can be 2, 3 or 4 cycles long, depending on what's most useful.

All this stuff is described in the original Motorola literature. I'd be surprised if Phase 5 has not implemented this, because it's not that hard to do.

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