pptanner@watcgl.waterloo.edu (Peter P. Tanner) (02/25/88)
We will be buying some frame buffer boards for a VMEbus based multiprocessor and are looking for some boards with a couple of peculiar characteristics. If anyone is aware of such boards, I would appreciate them letting me know. First of all, since tasks distributed over the different processors on the system require simultaneous access to the frame buffer, (a simple example of this would be two tasks, each responsible for a separate window, writing assynchronously to their own window), the frame buffer should have multiple register sets. Taking the write mask as an example, a single write mask is unusable. Sharing the write mask would require an unacceptable overhead. Several write masks, where the choice of write mask is made as part of the "write-to-frame-buffer" instruction (perhaps using some of the high-order bits in the 32 bit address of the frame buffer) is required. (The Adage/Ikonas 3000 has a scheme similar to this.) The second requirement is that the frame buffer be capable of variable frame rates up to 90 frame/sec non-interlaced. Last year, someone posted a request for information about VMEbus frame buffers on this net. If that person (or anyone else) has a synopsis of what is available, I would appreciate a copy.