Date: Sun, 29 May 2005 10:28:25 -0700 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: <questions@freebsd.org> Cc: Ulf Magnusson <ulfma629@student.liu.se>, freebsd-questions@freebsd.org Subject: RE: Seagate HD not detected by FreeBSD Message-ID: <LOBBIFDAGNMAMLGJJCKNCEJJFBAA.tedm@toybox.placo.com> In-Reply-To: <20050529134323.L20141@maren.thelosingend.net>
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> -----Original Message----- > From: owner-freebsd-questions@freebsd.org > [mailto:owner-freebsd-questions@freebsd.org]On Behalf Of Svein Halvor > Halvorsen > Sent: Sunday, May 29, 2005 4:49 AM > To: Ted Mittelstaedt > Cc: Ulf Magnusson; freebsd-questions@freebsd.org > Subject: RE: Seagate HD not detected by FreeBSD > > > > * Ted Mittelstaedt [2005-05-29 00:05 -0700] > > Wrong. Each IDE cable can have 2 devices a master and a > slave. So if > > you have 2 IDE controllers you can have master, slave, > master, slave > > for a total of 4 drives. > > > > It is not master on ide cable 1, slave on ide cable 2. > > > There's nothing wrong with having a primary master and a > secondary slave, > just as much as there is nothing wrong with the setup you proposes. > _______________________________________________ > According to the UDMA/66/100/133 standard, which REQUIRES an 80-pin cable, a SINGLE drive on the bus MUST BE connected to the BLACK end connector NOT to the GREY slave connector, OR to the BLUE motherboard connector. On this setup the BLUE end connector MUST BE connected to the motherboard. The only time it is permissible to connect a drive to the GREY slave connector is when there are TWO DRIVES on the cable. This requirement is because of cable termination issues - at high speed, an unterminated black connector with a terminated grey connector causes huge amount of noise and can disrupt high speed transfers. This is the same issue as SCSI cables, by the way. According to the Microsoft's PC97 AND the ATA Plug and Play standard, (ATA-2 and ATA-3) drive cables all must follow the Cable Select standard, AS MUST hard drives. CS removes pin 28 on the SLAVE connector. So on a correctly setup modern system, BOTH DRIVES have the CS jumper set, and if the drive is plugged into the black master connector it is automatically selected as master, and if the drive is unplugged from that connector and plugged to the grey connector it is automatically setup as a slave. Since the standard requires a single drive on the controller to be plugged into the end of the cable - for termination reasons - with CS set, by default the standard requires a single drive to be master. So yes, there is something wrong with a primary master and a secondary slave. Just because it works on a lot of motherboards, and just because it worked in the past on old incorrectly manufactured IDE cables, running in PIO mode, doesen't make it per-standard, and definitely doesen't make it right electrically if using CS, as per the standard. As I said already, motherboards take a lot of shortcuts and do a lot of non-standard things. Ted
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