Question about External HD
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From: Erik Richard Sørensen on 25 Jan 2010 16:38 Tom Stiller wrote: > nospam <nospam(a)nospam.invalid> wrote: >> they're both serial as far as the cabling goes, but you could say that >> firewire is more 'serial' since it is daisy chained, whereas usb is >> more 'parallel' since there are multiple devices off one hub. > > FireWire hubs exist also. Indeed they do - I have a 6-port Belkin FW400 right here managing my external harddisks. But I understand it so that 'nospam' here means that the built-in USB acts like an external powered USB hub, which it certainly doesn't.... Cheers, Erik Richard -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Erik Richard Sørensen, Member of ADC, <mac-manNOSP(a)Mstofanet.dk> NisusWriter - The Future In Multilingual Text Processing - www.nisus.com OpenOffice.org - The Modern Productivity Solution - www.openoffice.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From: nospam on 25 Jan 2010 18:35 In article <tom_stiller-20B9BE.16072925012010(a)news.individual.net>, Tom Stiller <tom_stiller(a)yahoo.com> wrote: > FireWire hubs exist also. true, but rarely used. they're also not required for multiple devices, whereas a usb hub is.
From: nospam on 25 Jan 2010 18:35 In article <4b5e0d79$0$8568$ba624c82(a)nntp06.dk.telia.net>, Erik Richard S�rensen <NOSPAM(a)NOSPAM.dk> wrote: > It is you who began talking about harddisks and SCSI - not me. I just > pointed it out to you that you can't compare anything like that with USB. i cited the 8mhz mac because back then, the cpu *did* matter. a 2.5 gigahertz core 2 duo is not going to be burdened by a couple of hard drives, especially when they are limited to usb speeds. > The 'problem' is that the USB still is a sort of serial construction > where each port is depending on the other ports. nope. > There are simply no Mac > computer with built-in independant USB circuitry. every mac since the dual usb ibook has independent usb ports. that's why it was called a dual usb. > > they're both serial as far as the cabling goes, but you could say that > > firewire is more 'serial' since it is daisy chained, whereas usb is > > more 'parallel' since there are multiple devices off one hub. > > For that manner you can also 'daisy-chain' USB devices, you absolutely cannot daisy chain a usb device to another device. only if there's a built-in hub can you attach another usb device, such as with a keyboard, but that's not daisy chaining, that's going through a hub, one that happens to be included with the device. also, they're usually bus-powered so the attached devices need to be low power. > but that doesn't > change anything since the transferred signal still is routed through the > cabling, which the FW signal isn't. firewire signals are not routed through cables?? so the cables are just for decoration?? > FW here is more like a cabled 'radio > transmitter', where you send multiple signals with slightly shifted > carrying signal frequencies to/from each FW device. this just gets even more bizarre. where did you read *that* ?
From: Erik Richard Sørensen on 25 Jan 2010 19:11 nospam wrote: > Erik Richard Sørensen <NOSPAM(a)NOSPAM.dk> wrote: >> It is you who began talking about harddisks and SCSI - not me. I just >> pointed it out to you that you can't compare anything like that with USB. > > i cited the 8mhz mac because back then, the cpu *did* matter. a 2.5 > gigahertz core 2 duo is not going to be burdened by a couple of hard > drives, especially when they are limited to usb speeds. > >> The 'problem' is that the USB still is a sort of serial construction >> where each port is depending on the other ports. > > nope. Sure it is. And sure it matters how many UsB devices you connect. It is obviously that you've never tried running with more than 1-2 maybe three USB external devices at a time. >> There are simply no Mac >> computer with built-in independant USB circuitry. > > every mac since the dual usb ibook has independent usb ports. that's > why it was called a dual usb. I have both worked with and seen rather many 'splashed' iBooks and PowerBooks for that matter - and none of these have had anything but 2 USB ports and that's why it is called the 'dual USB' model. >>> they're both serial as far as the cabling goes, but you could say that >>> firewire is more 'serial' since it is daisy chained, whereas usb is >>> more 'parallel' since there are multiple devices off one hub. >> For that manner you can also 'daisy-chain' USB devices, > > you absolutely cannot daisy chain a usb device to another device. > > only if there's a built-in hub can you attach another usb device, such > as with a keyboard, but that's not daisy chaining, that's going through > a hub, one that happens to be included with the device. also, they're > usually bus-powered so the attached devices need to be low power. Aha! Why can I then just connect one USB harddisk to the other, when there are both an USB A and an USB B port? - Nothing mentioned anywhere about built-in 'hubs' or things like that. - I also /have/ two harddisks with built-in hubs, but here it's explecitely mentioned that this a hub. These UsB ports can even be used, if the drive is connected via FW400, FW800 or eSATA. It is also clearly written in the guide that the USB ports are _balanced_ with _individual_ powering, but that doesn't mean that they are independant circuits. >> but that doesn't >> change anything since the transferred signal still is routed through the >> cabling, which the FW signal isn't. > > firewire signals are not routed through cables?? so the cables are just > for decoration?? When you use the term 'routed' you just use it as a 'signal carrier'. But a routed signal is depending on other signals in the same chain. - A Firewire signal isnot routed - only _carried_ through the cables. >> FW here is more like a cabled 'radio >> transmitter', where you send multiple signals with slightly shifted >> carrying signal frequencies to/from each FW device. > > this just gets even more bizarre. where did you read *that* ? Somewhere, but also tech guys use these terms to explain the way Firewire is handled to people, who doesn't know much about computer technology. Cheers, Erik Richard -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Erik Richard Sørensen, Member of ADC, <mac-manNOSP(a)Mstofanet.dk> NisusWriter - The Future In Multilingual Text Processing - www.nisus.com OpenOffice.org - The Modern Productivity Solution - www.openoffice.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From: nospam on 25 Jan 2010 19:44
In article <4b5e3331$0$4810$ba624c82(a)nntp02.dk.telia.net>, Erik Richard S�rensen <NOSPAM(a)NOSPAM.dk> wrote: > Sure it is. And sure it matters how many UsB devices you connect. It is > obviously that you've never tried running with more than 1-2 maybe three > USB external devices at a time. i have 7 usb devices on my desktop mac. > >> There are simply no Mac > >> computer with built-in independant USB circuitry. > > > > every mac since the dual usb ibook has independent usb ports. that's > > why it was called a dual usb. > > I have both worked with and seen rather many 'splashed' iBooks and > PowerBooks for that matter - and none of these have had anything but 2 > USB ports and that's why it is called the 'dual USB' model. from the developer note for the ibook dual usb: <http://developer.apple.com/legacy/mac/library/documentation/Hardware/De veloper_Notes/Macintosh_CPUs-G3/ibook08May01/ibook-17.html#25515> The Pangea IC implements two independent USB controllers (root hubs), each of which is connected to one of the ports on the back panel of the computer. The use of two independent controllers allows both USB ports to support high data rate devices at the same time with no degradation of their performance. If a user connects a high-speed (12�Mbps) device to one port and another high-speed device to the other, both devices can operate at their full data rates. read that last sentence a couple of times. > >> For that manner you can also 'daisy-chain' USB devices, > > > > you absolutely cannot daisy chain a usb device to another device. > > > > only if there's a built-in hub can you attach another usb device, such > > as with a keyboard, but that's not daisy chaining, that's going through > > a hub, one that happens to be included with the device. also, they're > > usually bus-powered so the attached devices need to be low power. > > Aha! Why can I then just connect one USB harddisk to the other, when > there are both an USB A and an USB B port? - Nothing mentioned anywhere > about built-in 'hubs' or things like that. which usb hard drive has both types of ports? > - I also /have/ two harddisks > with built-in hubs, but here it's explecitely mentioned that this a hub. exactly. if there's a usb a port, then there's a hub inside. > These UsB ports can even be used, if the drive is connected via FW400, > FW800 or eSATA. i've never seen a drive that can use both usb *and* firewire at the same time. some even have physical switches, although most auto-detect. which usb drive is this? > It is also clearly written in the guide that the USB > ports are _balanced_ with _individual_ powering, but that doesn't mean > that they are independant circuits. so what does it mean? > >> but that doesn't > >> change anything since the transferred signal still is routed through the > >> cabling, which the FW signal isn't. > > > > firewire signals are not routed through cables?? so the cables are just > > for decoration?? > > When you use the term 'routed' you just use it as a 'signal carrier'. > But a routed signal is depending on other signals in the same chain. - A > Firewire signal isnot routed - only _carried_ through the cables. link? > >> FW here is more like a cabled 'radio > >> transmitter', where you send multiple signals with slightly shifted > >> carrying signal frequencies to/from each FW device. > > > > this just gets even more bizarre. where did you read *that* ? > > Somewhere, 'somewhere' ? provide a link. this ought to be good. > but also tech guys use these terms to explain the way > Firewire is handled to people, who doesn't know much about computer > technology. that must be why they explained it to you that way. |