Drivers for SparcStation SS240 (Voyager)?

As part of my personal collection, I've recently brought a SparcStation Voyager back from the dead (wellllll, it was coughin' up blood last night....). After replacing the display (bad backlight) and the NVRAM (bad battery), I learned the machine bore Debian Linux (and I didn't have the passwords). I dug out a Solaris 2.6 CD and ran the automated install, and everything works! - except that it won't run the windowing system. Early in the boot process it complains about not finding the driver for the framebuffer. I verified that the framebuffer is seen on the Sbus (as a bwthree); that devalias showed a device called 'screen' looking to that framebuffer in the right place; that the framebuffer's slot was early in the Sbus probe; and since there wasn't a driver in /devices for bwthree, just on a chance I copied bwtwo to a file called bwthree. I am coming to the conclusion I have one of two problems: either I really need a particular driver for this framebuffer, or there's something I'm seriously misunderstanding in the process. In the former case, I hope there is someone out there who could share a file; in the latter, I hope he/she will share enlightenment. :-) Thanks -- Ian