Back to SP1?

So is it necessary to uninstall SP2 to get back the previously achieved performance? No. It is sufficient to install the operating system's old FireWire driver. In fact it is already enough to exchange two files [1]. Here's how to do it:

• Go to the the hidden Windows\Inf directory and copy 1394.inf to a new directory, like \1394_fix.

Before updating to SP2:

• Go to Windows\system32\drivers and copy ohci1394.sys and 1394bus.sys to \1394_fix. These files have a date around august 2002, and say SP1 in their file properties.

If you already updated to SP2: the old ohci1394.sys and 1394bus.sys are found in Windows\Driver Cache\i386\sp1.cab. Copy the files from this archive into the directory \1394_fix.

If you had not installed SP1: the files are found in driver.cab, but this archive includes older files that we did not test.

• Install the SP2 update
   
• Go to Windows\system32\drivers and copy these files to \1394_fix: arp1394.sys, enum1394.sys, nic1394.sys

These files are the ones from SP2. There is no need to reinstall all old FireWire drivers. Some of them haven't changed, others are for network use only.

These files are now also found in the sp2.cab, location see above.

• Rename sp2.cab to sp2_dead.cab.

This is necessary, as Windows includes a nice security mechanism, which prevents worst-case-users from accidentally overwriting important driver files with older versions, or even worse, deleting them completely. So if you try to install the mix of driver files in \1394_fix, Windows will automatically install the newer files found in its sp2.cab!

• Make sure the Fireface is switched off and no other external FireWire device is present.
   
• Go to Device Manager, FireWire controller (OHCI xxx, 1394 or similar), Properties, Driver, Driver Update. Select 'No, only this time', 'Install from a list or specific location (advanced)', click 'Next', select 'Don't search I will choose the driver to install', click 'Next', then 'Have Disk'. Now point to \1394_fix. Then continue.
   
• Windows will now ask for the path to the file ohci1394.sys and 1394bus.sys. It wants to install the newer ones (see above). Again point to \1394_fix.

That's it. You can now go to Driver Details, and verify that all driver files are from SP2 except the ohci1394.sys and 1394bus.sys, which are from SP1. Next reboot, switch on the Fireface, and check that the Fireface can perform record/playback.

Finally you can rename sp2_dead.cab back to sp2.cab. Windows will no longer try to copy the newer driver file until you do a reinstall of the FireWire controller driver. So it makes sense to activate the driver cache security mechanism again.

[1] In the first version of this Tech Info, only the file ohci1394.sys had been exchanged. With this, the throughput rises to good S400. But exchanging the 1394bus.sys as well will activate full 800 Mbit/s.