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mist64 / geos

Source code of GEOS 2.0 for the Commodore 64 and 128
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Feature drv1571burst #20

Open ytmytm opened 6 months ago

ytmytm commented 6 months ago

This is a 1571 driver meant only for VARIANT=bsw128 which uses native Burst Command Instruction Set (see chapter 10 of 1571 User's Guide).

The speed is comparable to the BSW driver, but the drive is not running speed code, so EnterTurbo / ExitTurbo calls do nothing and there is no need to reset the drive.

I put it on hold in March 2002 just to complete now.

ytmytm commented 5 months ago

I'm dumb - this can be twice as fast as BSW code. I could notice that only when using track caching on expanded 1571 (https://github.com/ytmytm/1571-TrackCacheROM).

Simply put - when testing on original disks it does nothing because sector interleave is suboptimal. What is gained on transfer speed it lost on waiting for the next sector in the chain.

Now to figure out the optimal interleave value here.