Make a PC Look Like a Firewire or USB Drive?

buckinm asks: "Here's the problem: I have a Windows laptop that I use for work. When I'm at home though, I much rather use my Mac. Since we use Cisco's VPN client at work, I can't mount the drives on the PC from the Mac. What I'd like to know, is there any software out there that would make the PC act like a Firewire or USB drive? I'd want to be able to mount it read/write. I know I could do some sort of rsync of thing when not connected to the VPN, but that seems like too much trouble. I wouldn't be against writing something like that, if I could get some idea of what is required to listen / respond to traffic on the Firewire or USB ports."

Possible, I think

[MBCook]

I see no reason that it shouldn't be possible. Macs can do this. You boot them while holding "F" or "D" or "Command-F" or "Command-D" or something. They sit there and act like a firewire disk. I think you can even access the CD drive in them.

As for the PC side, I don't know. It's obviously possible, but I haven't heard of it. The Tinkerer in me says make a switch that disconnects the HD from the computer and connects it to a IDE->Firewire adaptor you hide in the case. Switch in one position it's a normal computer. Switch in the other it's a firewire disk.

Good luck.

ive only used firewire 3 times in my life but...

[ForestGrump]

the firewire interface has a tcp/ip stack.

Seriously, Macs just work.

[Anonymous Coward]

SCSI and FireWire Disk Modes
2000.11.29
Paulo Rodrigues

Our Fair Computer Company has released some quirky yet useful features in its computer systems and OS, and then advertised them very little, if at all. Apple's SCSI Disk Mode, and it's modernized offspring, FireWire Target Disk Mode, are excellent examples.
SCSI Disk Mode

SCSI Disk Mode, introduced way back in October 1991 on the PowerBook 100, allowed you to mount your PowerBook's hard drive on another Mac using a funny $30 cable made called PowerBook 100 Seriesthe SCSI Disk Adaptor. (Apple changed its name to HD Target Mode starting with the 5300 and 190, since they used IDE hard drives, but it works the same way. For consistency I'll refer to them both as SCSI Disk Mode.)

While today you can do the same thing with File Sharing and a $15 ethernet "crossover" cable, on most models you're limited to the relatively poor bandwidth of 10 megabit per second ethernet. Also, if your PowerBook has no ethernet port, you'd need to buy either an expensive PC Card ethernet adaptor or a speed-squashing LocalTalk-to-Ethernet bridge.

I'll refer to the Mac acting as an external hard drive as the "target" Mac, like Apple does, and the connecting computer as the "host" Mac.

Setup of SCSI Disk Mode

1. Shut down both machines.
2. Connect your SCSI Disk Adaptor between the target PowerBook and the host Mac.
3. Start up the target PowerBook. A SCSI icon and ID number should appear on the screen.
4. Turn on any other SCSI devices if the PowerBook is not the only device on the SCSI chain.
5. Start up the host Mac.
6. The PowerBook's hard drive icon should mount on the desktop of the host Mac. You can use it like you would use an external drive with little speed loss over using the PowerBook's drive in the PowerBook.

Okay, so it's not true plug-and-play ease, but it's a really convenient feature if you have an older PowerBook and another Mac with SCSI and can get your hands on the hard-to-find SCSI Disk Adaptors.

* Note that the PowerBook 140, 145, 145b, 150, and 170 do not support SCSI Disk Mode.

FireWire Target Disk Mode

Apple stopped including SCSI with the 2000 PowerBooks, replacing the SCSI port with two of Apple's more-Indigo iBookmodern FireWire ports. So you're in the dark if you wanna drop a huge file onto a new PowerBook's hard drive at full speed, right?

Of course not! Apple cleverly designed a new FireWire-based technology, called FireWire Target Disk Mode, which lets you connect your new PowerBook to another FireWire-equipped Mac. When Apple announced its new iBooks last September -- which also come with FireWire -- it included FireWire Target Disk Mode on them as well. As with its SCSI counterpart, the vast majority of 2000 PowerBook and iBook don't know such a feature exists!

Setup of FireWire Target Disk Mode is almost too easy:

1. Shut down the target Mac, leaving the host computer running.
2. Connect an ordinary 6-pin to 6-pin FireWire cable to a FireWire port on both computers. (These can be bought for around $15.)
3. Start up the target Mac and hold down the "T" key. A FireWire icon will appear on the screen, and the hard drive icon of the target Mac will pop up onto the host Mac's desktop.

Compared to SCSI Disk Mode, FireWire Target Disk Mode requires no rebooting of the host Mac and needs only an easy-to-find FireWire cable (it's half the price of the SCSI Disk Adaptor). FireWire Target Disk Mode is the fastest and easiest way to send files between a new portable Mac and any other Mac with FireWire. For sharing files between PowerBooks, FireWire provides 100 times the bandwidth of IrDA, the bigwig in Windows notebook computer and Palm PDA file sharing.

One other nicety is that FireWire Target Disk Mode is hot pluggable, you don't have to plug the two computers together before you start up the "target" PowerBook or iBook. Once the target computer has booted and the FireWire icon

Re:Possible, I think

[Joseph Vigneau]

Because the motherboard manufacturer's only control the motherboard, and in some cases either the video card or the CPU, not the memory, hard drive, sound card, TV tuner card, Firewire card, network card or pretty much anything else that Apple keeps tightly under their control.

More and more motherboards have this stuff on board, particularly Firewire and USB controllers. With a smarter BIOS (maybe even LinuxBIOS [linuxbios.org]), those manufacturers could provide a service similar to Apple's Target Disk Mode.

FWIW, Apple doesn't have tight control over drives and memory; these are commonly swapped out with commodity parts with higher capacity by end users.

And, as someone else mentioned here, there's at least one PC laptop manufacturer that has this feature.

Same thing, for Pocket PCs?

[Kris_J]

Is there a program that will make my Pocket PC (Asus 716) behave like a normal USB drive so I can copy stuff on and off of it without needing the ActiveSync app installed?

FireWire? Likely. USB? I doubt it.

[veliath]

FireWire host-controllers in PCs are symmetric as far as I know, so you could theoretically have a PC behave like a FireWire drive (i.e. speak SBP2). The protocol itself is a form of RDMA - which means FireWire controllers export their hosts as addressable 48bit memory ranges. Should be symmetric.

USB host-controller in PCs are different. In USB, only the host-controller can bus-master - i.e. initiate transactions on the USB bus - no other device on the bus can. I believe this is specified in the protocol itself. The protocol allows for a smart host-controller and dumb devices. One master and the rest slaves.

This might become clearer if you examine the terminology. The ports closest to the host-controller are said to belong to the "root hub". USB provides for a tree architecture, rooted at the host-controller's ports.

This means that you cannot connect two PCs back-back through their USB ports and say run PPP over them. AFAIK host-controllers in PCs do not have a slave mode that they can be switched to.

The PC emulating a hard-disk has to be able to become a slave to show up as a device.

veliath