DreamShell 4.0 RC 3

[SWAT]

It's not a simple as you think.
Optical and hard disks reads data all time, because disk is spinning, so controller reads data to cache constantly. Getting from cache much faster than reading from disk and it's equivalent to the bus speed. If at reading need move the head, then first reading will be slow, if need read from current head offset, then reading will be fast. The game developers known it and and try to read data linearly.
Also G1 Bus doesn't support UDMA modes, just WDMA (mode 2 max).

Here is an excerpt from the doc:

Цитата:Single density area approx. 600KB/s (4x speed)
Double density area approx. 900 (6x speed) - 1800 KB/s (12x speed)
From the buffer approx. 11.1 MB/s (PIO Mode3)
Approx. 13.3 MB/s (Multi word DMA Mode2)

At reading from HDD we can get avg ~11-13 MB/s, so it's equivalent to reading from the cache.