Framebuffer - History

History

Computer researchers had long discussed the theoretical advantages of a framebuffer, but were unable to produce a machine with sufficient memory at an economically practicable cost. In 1969, Joan Miller of Bell Labs experimented with the first known instance of a framebuffer. The device displayed an image with a color depth of three bits. However, it was not until the 1970s that advances in integrated-circuit memory made it practical to create the first framebuffer capable of holding a standard video image.

In 1972, Richard Shoup developed the SuperPaint system at Xerox PARC. This system had 311,040 bytes of memory and was capable of storing 640 by 480 pixels of data with 8 bits of color depth. The memory was scattered across 16 circuit boards, each loaded with multiple 2-kilobit shift register chips. While workable, this design required that the total framebuffer be implemented as a 307,200 byte shift register that shifted in synchronization with the television output signal. The primary drawback to this scheme was that memory was not random access. Rather, a given position could be accessed only when the desired scan-line and pixel time rolled around. This gave the system a maximum latency of 33 ms for writing to the framebuffer.

Shoup was also able to use the SuperPaint framebuffer to create an early digital video-capture system. By synchronizing the output signal to the input signal, Shoup was able to overwrite each pixel of data as it shifted in. Shoup also experimented with modifying the output signal using color tables. These color tables allowed the SuperPaint system to produce a wide variety of colors outside the range of the limited 8-bit data it contained. This scheme would later become commonplace in computer framebuffers.

In 1974 Evans & Sutherland released the first commercial framebuffer, costing about $15,000. It was capable of producing resolutions of up to 512 by 512 pixels in 8-bit grayscale, and became a boon for graphics researchers who did not have the resources to build their own framebuffer. The New York Institute of Technology would later create the first 24-bit color system using three of the Evans & Sutherland framebuffers. Each framebuffer was connected to an RGB color output (one for red, one for green and one for blue), with a minicomputer controlling the three devices as one.

In 1975, the UK company Quantel produced the first commercial full-color broadcast framebuffer, the Quantel DFS 3000. It was first used in TV coverage of the 1976 Montreal Olympics to generate a picture-in-picture inset of the Olympic flaming torch while the rest of the picture featured the runner entering the stadium.

The rapid improvement of integrated-circuit technology made it possible for many of the home computers of the late 1970s (such as the Apple II) to contain low-color framebuffers. While initially derided for poor performance in comparison to the more sophisticated graphics devices used in computers like the Atari 400, framebuffers eventually became the standard for all personal computers. Today, nearly all computers with graphical capabilities utilize a framebuffer for generating the video signal.

Framebuffers also became popular in high-end workstations throughout the 1980s. SGI, Sun Microsystems, HP, DEC and IBM all released framebuffers for their computers. These framebuffers were usually of a much higher quality than could be found in most home computers, and were regularly used in television, printing, computer modeling and 3D graphics.

Amiga computers, due to their special design attention to graphics performance, created in the 1980s a vast market of framebuffer based graphics cards. Noteworthy to mention was the graphics card in Amiga A2500 Unix, which was in 1991 the first computer to implement an X11 server program as a server for hosting graphical environments and the Open Look GUI graphical interface in high resolution (1024x1024 or 1024x768 at 256 colors). The graphics card for A2500 Unix was called the A2410 (Lowell TIGA Graphics Card) and was an 8-bit graphics board based on the Texas Instruments TMS34010 clocked at 50 MHz. It was a complete intelligent graphics coprocessor. The A2410 graphics card for Amiga was co-developed with Lowell University. Other noteworthy Amiga framebuffer based cards were: the Impact Vision IV24 graphics card from GVP, an interesting integrated video suite, capable of mixing 24-bit framebuffer, with Genlock, Chromakey, TV signal pass-thru and TV in a window capabilities; the DCTV a graphics card and video capture system; the Firecracker 32-bit graphics card; the Harlequin card, the Colorburst; the HAM-E external framebuffer. The Graffiti external graphics card is still available on the market.

Most Atari ST (Mega STE model), and Atari TT framebuffers were created for the VME rear connector slot of Atari machines dedicated to video expansion cards: Leonardo 24-bit VME graphics adapter, CrazyDots II 24-bit VME graphics card, Spektrum TC graphics card, NOVA ET4000 VME SVGA graphics card (capable of resolutions up to 1024x768 at 256 colors or 800x600 at 32768 colors), whose design came from the ISA/PC world (it was effectively an ATI Mach32 S: with 1 MB of video RAM).