[TUHS] Re: Origins of the frame buffer device

I would think you have read Sutherland's "wheel of reincarnation" paper, but if you haven't, please do. What fascinates me today is that it seems for about a decade now the bearings on that wheel have rusted solid, and no one seems interested in lubricating them to get it going again. -rob On Mon, Mar 6, 2023 at 7:52 PM Paul Ruizendaal via TUHS <tuhs(a)tuhs.org> wrote: > Thanks for this. > > My question was unclear: I wasn't thinking of the hardware, but of the > software abstraction, i.e. the device files living in /dev > > I’ve now read through SunOS man pages and it would seem that the /dev/fb > file was indeed similar to /dev/fbdev on Linux 15 years later. Not quite > the same though, as initially it seems to have been tied to the kernel part > of the SunWindows software. My understanding of the latter is still limited > though. The later Linux usage is designed around mmap() and I am not sure > when that arrived in SunOS (the mmap call exists in the manpages of 4.2BSD, > but was not implemented at that time). Maybe at the time of the Sun-1 and > Sun-2 it worked differently. > > The frame buffer hardware is exposed differently in Plan9. Here there are > device files (initially /dev/bit/screen and /dev/bit/bitblt) but these are > not designed around mmap(), which does not exist on Plan9 by design. It > later develops into the /dev/draw/... files. However, my understanding of > graphics in Plan9 is also still limited. > > All in all, finding a conceptually clean but still performant way to > expose the frame buffer (and acceleration) hardware seems to have been a > hard problem. Arguably it still is. > > > > > On 5 Mar 2023, at 19:25, Kenneth Goodwin <kennethgoodwin56(a)gmail.com> > wrote: > > > > The first frame buffers from Evans and Sutherland were at University of > Utah, DOD SITES and NYIT CGL as I recall. > > > > Circa 1974 to 1978. > > > > They were 19 inch RETMA racks. > > Took three to get decent RGB. > > > > 8 bits per pixel per FB. > > > > On Sun, Mar 5, 2023, 10:02 AM Paul Ruizendaal via TUHS <tuhs(a)tuhs.org> > wrote: > > I am confused on the history of the frame buffer device. > > > > On Linux, it seems that /dev/fbdev originated in 1999 from work done > by Martin Schaller and Geert Uytterhoeven (and some input from Fabrice > Bellard?). > > > > However, it would seem at first glance that early SunOS also had a > frame buffer device (/dev/cgoneX. /dev/bwoneX, etc.) which was similar in > nature (a character device that could be mmap’ed to give access to the > hardware frame buffer, and ioctl’s to probe and configure the hardware). Is > that correct, or were these entirely different in nature? > > > > Paul > > > >