DOS code in CP/M? Revisited...
abuse at cabal.org.uk
Sat Jul 16 06:12:00 CDT 2016
On Fri, Jul 15, 2016 at 08:10:24PM +0200, Liam Proven wrote:
> I vividly remember reading it as a 19YO student...
> "The hard disk in the A500 is most noticeable for its ferociously rapid
> access speed. It loads huge programs with a faint burping noise, in the time
> it takes to blink an eye. The reason for this speed is that the disk is run
> with no interleaving of sectors. On an IBM XT, for example, the disk rotates
> about six times between each read to give the puny CPU time to digest;
> Archimedes eliminates this dead time as the ARM processor can suck stuff off
> the disk as fast as it can rotate."
Isn't that mostly down to the difference between polled- and DMA-driven I/O?
Not that IBM should be given any slack, given what a complete dog's breakfast
ISA DMA is.
Back in 1987, the Amiga had crap hard disk performance because while the
controllers generally supported DMA, the disks still had to be formatted with
that awful filesystem it inherited from Tripos. (This wasn't fixed until 1988.)
I wonder how the Atari ST fared back then. Probably reasonably well given its
filesystem is a FAT derivative.
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