I posted in part in comp.sys.ibm.pc.hardware.storage
on March 31, 2004:
interference in the performance. I occurs to me that much of the
variation that is seen due to timing granularity and the fact
that the DiskSpeed32 program reports timing for "logical" cylinders,
of which there are 24792 on one of the disk types that I tested, while
there are 395136 actual cylinders on the Maxtor 6Y200P0. This
means that some "cylinders" have more actual cylinders than others.

Also, some people questioned that a disk, as opposed to a drum,
would have the number of tracks in a cylinder here:
the price I quoted a typical drive might have 11 platters, with
recording on 20 surfaces, one of which was for timing. This yields
19 tracks per cylinder. Some drives had 2 or 4 heads on each data
surface, yielding 38 and 76 tracks per logical cylinder.
, rather than 2, 4, or 8

Also folks:
Please post to USENET groups, not copies of the groups that are
maintained by private services: many of these don't get back to the
USENET groups world and can only be found by Google or similar
searches, rather than reading the USENET groups at just about any
ISP.

"Mark Fineman" <mark.s.fineman@verizon.net> wrote in message news:8pss80pnu22o65aal76cpbk9vv48f5sc45@4ax.com...
Nope.
It means that logical cylinders are not comparable to physical cylinders.
Drives translate logical CHS (P-CHS) to LBA and then to a physical CHS
(for IDE). And CHS (*whether L-CHS or P-CHS) is even limited to 8GB.

*
L-CHS is logical CHS at the program side of a translating bios
P-CHS is logical CHS at the ATA interface side of a translating bios

On SCSI the bios translates directly to LBA. IDE can do this too.
Physical CHS these days is described by zone cylinder head and sector (ZCHS)

Well, that redefines the word cylinder when in logical terms the cylinder
is actually 2 or 4 physical (in the visual sense) cylinders.