[TUHS] Re: Origins of the frame buffer device

[Henry Bent <henry.r.bent@gmail.com>]

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The paper Rob refers to is https://dl.acm.org/doi/10.1145/363347.363368

-Henry

On Mon, 6 Mar 2023 at 03:57, Rob Pike <robpike@gmail.com> wrote:

> 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@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@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@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
>> >
>>
>>

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