USB 2.0's ACTUAL transfer rate??

[bjc112]

480Mbps comes about to be about 50-60 MB/s...

What is the actual sustained transfer rate? 20-30MB/s??

How about firewire? ! Is 400Mbps capable?

Does it vary between flash drives and microdrives?



I was flipping through a USB 2.0 thumb drive i had, and the actual write performance was on 7MB/s..

Thanks!

 

[LoudTIGER]

firewire > usb2

 

[MScrip]

USB 2.0 is designed with a 480Mbps maximum transfer rate... whether or not you'll ever achieve that is a different story.

 

[TerryMathews]

Originally posted by: bjc112
I was flipping through a USB 2.0 thumb drive i had, and the actual write performance was on 7MB/s..

That would be because it's a thumb drive, nothing to do with the bus it's on. In case you didn't know, a thumb drive is a EEPROM, or more commonly referred to as a flash rom. Moderate read speeds, slow writes.

I've got an Archos Jukebox Recorder 20 (USB 2.0) and an Apple iPod 3g 40GB (Firewire). Both transfer at a rate you'd expect for a 4000RPM 2MB buffer 2.5" HDD.

If you're USB2.0/Firewire is on-chipset, you'll probably achieve close to the maximum 480mbit/sec IF there is only one device connected to the bus and you've got a device that can sustain that transfer rate. AFAIK, no such device exists.

 

[bjc112]

Originally posted by: TerryMathews

Originally posted by: bjc112
I was flipping through a USB 2.0 thumb drive i had, and the actual write performance was on 7MB/s..

That would be because it's a thumb drive, nothing to do with the bus it's on. In case you didn't know, a thumb drive is a EEPROM, or more commonly referred to as a flash rom. Moderate read speeds, slow writes.

I've got an Archos Jukebox Recorder 20 (USB 2.0) and an Apple iPod 3g 40GB (Firewire). Both transfer at a rate you'd expect for a 4000RPM 2MB buffer 2.5" HDD.

If you're USB2.0/Firewire is on-chipset, you'll probably achieve close to the maximum 480mbit/sec IF there is only one device connected to the bus and you've got a device that can sustain that transfer rate. AFAIK, no such device exists.

EEPROM... Ok..

Good info to know.

Thanks!


"Firewire >USB2"


Of course

 

[Yanagi]

Yeah, that seems about correct. Also remember when having more than one device installed it shares the bandwidth. so if you have 10 usb devices installed bandwidth for each device is gonna be 480/10=48Mbit/s

 

[bjc112]

Originally posted by: Yanagi
Yeah, that seems about correct. Also remember when having more than one device installed it shares the bandwidth. so if you have 10 usb devices installed bandwidth for each device is gonna be 480/10=48Mbit/s

Well, im talking single device, max bandwidth.. Yet consistent transfer rate.

What about microdrives? Are they considered EEPROM? Faster sustained transfers?

Thanks

 

[MScrip]

Think of USB as a road... and the speed of the cars depends on the cars themselves. The road has a speed limit... but each car will go as fast as it can.

USB 2.0 has a limit of 480Mbps... but the actual speed varies depending on the devices connected to it.

A fast hard drive will transfer data faster over USB than a slow hard drive. Each device has it's own speed rating.

 

[Mday]

Um, how are you going to ask what the actual transfer rate of a protocol is? That makes no sense. Its like asking how fast you drive on a road that has a speed limit of 60 MPH.

EEPROMs are SLOW AS HELL! Flash memory is NOT EEPROM. Microdrives are MINIATURE hard drives with a tiny spinning platter.

 

[TerryMathews]

Originally posted by: Mday
Flash memory is NOT EEPROM. Microdrives are MINIATURE hard drives with a tiny spinning platter.

You are technically correct. That said, flash memory is close enough to EEPROM for this discussion. It's a common, if antequated term that most computer people understand.

And to the question about Microdrives: They do have faster write speeds. Not fast enough to make a difference however.

 

[So]

Originally posted by: bjc112

Originally posted by: TerryMathews

Originally posted by: bjc112
I was flipping through a USB 2.0 thumb drive i had, and the actual write performance was on 7MB/s..

That would be because it's a thumb drive, nothing to do with the bus it's on. In case you didn't know, a thumb drive is a EEPROM, or more commonly referred to as a flash rom. Moderate read speeds, slow writes.

I've got an Archos Jukebox Recorder 20 (USB 2.0) and an Apple iPod 3g 40GB (Firewire). Both transfer at a rate you'd expect for a 4000RPM 2MB buffer 2.5" HDD.

If you're USB2.0/Firewire is on-chipset, you'll probably achieve close to the maximum 480mbit/sec IF there is only one device connected to the bus and you've got a device that can sustain that transfer rate. AFAIK, no such device exists.

EEPROM... Ok..

Good info to know.

Thanks!


"Firewire >USB2"


Of course

EEPROM is NOT in a flash drive. NO! BAD!

EEPROM is flash rom, but a thumb / flash drive has Flash RAM which is different.

 

[So]

Originally posted by: Mday
Um, how are you going to ask what the actual transfer rate of a protocol is? That makes no sense. Its like asking how fast you drive on a road that has a speed limit of 60 MPH.

EEPROMs are SLOW AS HELL! Flash memory is NOT EEPROM. Microdrives are MINIATURE hard drives with a tiny spinning platter.

Microdrives are an IBM tech, that is also completely different than Flash Memory (which is what is in a USB thumb drive).

 

[TerryMathews]

Originally posted by: So

EEPROM is NOT in a flash drive. NO! BAD!

EEPROM is flash rom, but a thumb / flash drive has Flash RAM which is different.

Nope. Nice try though.

Mano's "Logic and Computer Design Fundamentals" 3rd edition states clearly that flash memory drives use a modified version of EEPROM technology.

Flash RAM would be an oxymoron, since RAM by definition is volatile storage - IE you remove power data is gone.

 

[JeremiahTheGreat]

RAM, by definition, is Random Access Memory

 

[VirtualLarry]

Yeah, Flash is basically just an upgraded version of EEPROM. I think that they were originally called "flash", because when you erased them, it erased the entire chip all at once. Nowadays, that isn't true, there is both chip-, sector- and byte-erasable/addressable flash memory, using both NAND and NOR flash memory cells, in both serial and parallel-addressable configurations. Whew.

Most EEPROMs were (I think, don't have a lot of experience with them) byte-erasable, and parallel-addressable, like ROM and DRAM chips.

And to answer the OP's question, I think that in the real world, Firewire 400 will perform better than USB 2.0 Hi-Speed 480Mb/s, because of the overhead inherent in the crappy USB protocol.

Btw, does USB 2.0 still "burn" 10-15% of the bandwidth, just for error-detection for a "jabbering" device on the bus? I always thought that was one of the stupidest design decisions ever, especially in terms of limitations on latency and real-time devices connected to the bus.