[Pc_Support] External SATA bracket ($9), external SATA enclosure/power ($35)

[Bryan J. Smith]

"Bryan J. Smith" <b.j.smith at ieee.org> wrote:
> It's actually _not_ a "bus" in the traditional sense -- it's an
> end-device to the _other_ bus arbitrator (e.g., PCI).  That's
> why the term "channel" is used -- there's _no_way_ to actually
> "target" the master or slave (long story).  There is _no_
> "addressing" on a "bus" in ESDI or ATA.
> Only one device can be on the channel at a time.  The
> master/slave setup is a PIO select to enable one drive or 
> another.

I'm going to write a blog article on this.

>From the original ST506 MFM/RLL "disk controller" for 8/16-bit ISA to
the 16-bit ISA Enhanced System Disk Interface (ESDI) with it's _lack_
of a dedicated controller but "end-point" Integrated Drive
Electronics (IDE) on the hard drives themselves to Western Digital
re-hacking of IDE into Enhanced IDE (EIDE) into allowing a
master/slave relationship that was compatible with the ST506/CMOS
setup to the introduction of the PC/AT Attachment (ATA) standard with
Direct Memory Access (DMA) instead of Programmed I/O (PIO) and why
you should _never_ use master/slave with ATA DMA.



-- 
Bryan J. Smith     Professional, Technical Annoyance
b.j.smith at ieee.org      http://thebs413.blogspot.com
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*** Speed doesn't kill, difference in speed does ***