🚀 go-pugleaf

In article <5141@nigel.udel.EDU> new@udel.edu (Darren New) writes:
> Something else I don't understand: 
> The disk should be able to read about 5 tracks/second if you look only
> at the revolutions.  Yet when doing something like DiskCopy, the disk
> takes more than one second/track to read or write.  What's the slowdown?
> Is the blitter and system overhead really four times the read speed?

First of all, you have to read about 1.1 revolutions to be sure to get
a complete copy of each sector.  Then remember that you need to read both
top and bottom surfaces, and write the worst-case (slowest rotation speed)
track, which is a bit under 1.1 nominal tracks.

That adds up to 4.4 rotations to copy a cylinder, of which a 90mm floppy
has 80.  70.4 seconds.  The fastest copy program I know takes 69 seconds,
so it's pretty close.  It, I believe, reads one track while processing
the track before so it's always reading or writing.  This hides essentially
all the blitter overhead.  But Diskcopy isn't quite as smart.
-- 
	-Colin