LaserWriter/LocalTalk Bridges with Open Transport
There seems to be a bit of confusion about the status of Apple’s LaserWriter Bridge and LocalTalk Bridge with regard to Open Transport. These bridges, allow a machine connected to both a LocalTalk and an Ethernet network segment to act as a "bridge" between the two networks. Apple’s LaserWriter Bridge (as the name implies) allows a LocalTalk LaserWriter to be shared with an Ethernet network; the LocalTalk Bridge allows the full range of AppleTalk services to travel back and forth across the two types of networks.
To date, the released versions of the bridges (2.0.1) are not compatible with any version of Open Transport. Apple’s LaserWriter Bridge and LocalTalk Bridge software were designed to check for a specific version of AppleTalk software, and because Open Transport registers itself as a more recent version, the bridges will not launch.
Although Apple-supported updates for Open Transport-compatibility are currently underway (to be released as version 2.1), they are presently only available to developers. For now, the only work around is a temporary patch that modifies the bridges’ version check to recognize Open Transport.
The patch is available in two flavors, one for LaserWriter Bridge and one for LocalTalk Bridge:
- LaserWriter Bridge OT Patch only works on LaserWriter Bridge (2.0.1) from the Network Software Installer 1.5.1-ZM or the System 7.5 Update 2.0.
- LocalTalk Bridge OT Patch works with LocalTalk Bridge (v2.0.1). If you had v2.0 installed, the patcher will first update the software to v2.0.1 and then apply the patch.
Make sure to use the appropriate patch for your version of LaserWriter or LocalTalk Bridge. For those brave enough to use ResEdit to apply the patch manually, you can do the following:
- Open the FRED resource 128 (named "Mnd")
- At HEX 0448, change the "<" to an "="
The patch should work on all Macintosh computers (including PCI Power Macs and clones) using Open Transport version 1.0.8 or higher. Please note this patch has not been tested extensively; it is considered a hack and should be treated as such. If you have any doubts in applying this patch to your software, wait for the Apple-supported update which should appear soon.