8514 / A

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IBM Display Adapter 8514 / A

8514 / A describes both a graphics accelerator , which was introduced by IBM in 1987 together with the IBM PS / 2 series of computers ( Display Adapter 8514 / A ), and the associated graphics standard .

description

The 8514 / A standard is designed to complement the possibilities of VGA and uses a fixed resolution of 1024 × 768 image points ( pixels ) - around 2.5 times that of VGA (640 × 480 pixels). From a color palette of 262,144 colors, 256 can be displayed at the same time; The 8514 / A displays 64 gray levels on monochrome monitors. In addition, graphic commands for displaying vector graphics are defined.

technology

The original IBM Display Adapter 8514 / A did not have its own text or VGA capabilities. Instead, these functions are still taken over by the VGA graphics hardware, which is permanently installed in the PS / 2 models of the time, and forwards the generated image to the 8514 / A via a special slot on the MicroChannel bus. The 8514 / A itself only generates an image when its capabilities are requested. Depending on your needs, the VGA or 8514 / A image output is converted into a signal for the screen.

The concept that an application program to generate an image in the 8514 / A mode does not need to access the graphics hardware directly as before is still considered to be groundbreaking. Instead, a driver program runs in the background which, with the so-called Adapter Interface (AI), provides an interface with abstract graphic functions for other programs , which it converts into hardware commands. Because of this special feature, the 8514 / A or the AI ​​interface became the standard. However, it also made it possible for third-party manufacturers to produce their own compatible products ( clones ) without having to know the hardware of the original 8514 / A - as long as they provide a program that is compatible with the AI ​​of the 8514 / A and which is usually completely different Can control hardware.

The combination of resolution and color depth, which was remarkable for 1987, placed correspondingly higher demands on the size of the graphics memory and on the ability to output all of its content on the screen with sufficient speed. The IBM Display Adapter 8514 / A purchases this service through the use of the line jump procedure ("interlacing"), in which only every second line of the image is displayed at the same time, which also reduces the demands on the screen. Since this technology halves the effective refresh rate to 43.5 Hz, so that the image is perceived as flickering, some manufacturers later produced 8514 / A clones without this process ("non-interlaced").

In contrast to the original IBM original, clones were not only produced for the MicroChannel bus, but may also be full graphics cards with their own text, VGA and other functions.

equipment

The graphics memory of the IBM Display Adapter 8514 / A is 512 kB, which means that only 16 colors can be displayed. In order to actually be able to display 256 colors at the same time, an additional graphics memory expansion of 1 MB is required.

IBM sold the 8514 monitor to match the 8514 / A card, which can display the required 1024 × 768 pixels on a 16 " picture tube at 43.5 Hz (as well as the image modes of the VGA hardware). But anyone can do it too Another monitor with a VGA connection that achieves at least the same performance data can be used.

successor

In the fall of 1990, IBM published the XGA standard as its successor , which combined both VGA and 8514 / A-like functions in the same hardware. The successor to graphics accelerators came in 1989 with the Image Adapter / A , which met the highest demands.

literature

  • Jake Richter, Bud Smith: Graphics Programming for the 8514 / A . M&T Books, 1990, ISBN 1-55851-086-9 .

Web links

Individual evidence

  1. ↑ Louis Ohland: Technical information on the Display Adapter 8514 / A (English), accessed on February 5, 2014.