Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!bbn!rochester!uhura.cc.rochester.edu!ur-valhalla!micropen!dave From: dave@micropen (David F. Carlson) Newsgroups: comp.unix.microport Subject: Re: Bell Tech W.G.E. use with "sissy" unix Summary: non-issue Message-ID: <554@micropen> Date: 5 Oct 88 15:25:10 GMT References: <438@l5comp.UUCP> <428@eecea.eece.ksu.edu> Organization: Micropen Dirent Writing Systems, Pittsford, NY Lines: 24 In article <428@eecea.eece.ksu.edu>, terry@eecea.eece.ksu (Terry Hull) writes: > In article <438@l5comp.UUCP> scotty@l5comp.UUCP (Scott Turner) writes: > >Sanity check, can you even USE the W.G.E. card? > > > >That isn't as silly as it sounds. The driver supplied for the card maps > >the 82786's registers into memory so they can be accessed rapidly and > >easily. But if your system has a SRAM cache you may be in for a VERY > >nasty surprise! I have used machines with several caching schemes (Intel chips and Everex proprietary) and they always cache only memory they known about: main mother board memory. If a device has a memory map in the AT bus structure *it* must provide the dual port as there is no bus sharing per se in the AT bus. Therefore, the WGE has dedicated space in the device memory range, 0xc0000-> 0xdffff nearby the other major device memory: your graphics memory space. No caching is done of these areas or no polling IO would ever succeed. (I'm pretty sure it does. :-) DOS is no different from UNIX in this regard.) -- David F. Carlson, Micropen, Inc. micropen!dave@ee.rochester.edu "The faster I go, the behinder I get." --Lewis Carroll