either be used as a simple character display with user defined typefaces and simultaneously as an all-points addressable graphics display. Additionally, the controller had hardware assist features for drawing straight lines and sectors of circles. It would draw pixels along a line, a circular arc or from user defined characters in under 800 ns. This released the host computer to continue other processing while the drawing operation continued. The high-resolution capability permitted support for glyph-based languages like Japanese that were difficult to comprehensively support with character-based displays. The large memory space, combined with hardware viewport registers permitted smooth high-speed scrolling. Compatibility with Direct memory access hardware made it possible to move bitmaps to and from the controller memory at bus-limited rates. In this way, bitmaps could be Blitted around the display at high speed and the controller kept focused on the more complex rendering tasks. The controller could address a maximum 1024 x 1024 pixel display with four-bit colour depth. It included a light pen interface that synchronised the pixel clock to input signals without additional processor support. GKS was available on CP/M and MS-DOS systems and formed the basis of early 1980s CAD platforms on otherwise limited hardware platforms. A few years after its introduction, one journalist said "The 7220 GDC chip is a component that even some of NEC's competitors have found too good to pass up." When the Apple Lisa was announced in 1983, the press raised questions on why the popular 7220 was not used. Bruce Daniels pointed out that the Lisa primarily used raster graphics (known as bitmap graphics at the time), which could be implemented with less expensive hardware support. Instead, graphics primitives were written in software. Development manager Wayne Rosing added that although the team knew about the 7220, it was not quite available when the design began. There were also restrictions on when the display memory could be accessed: only during certain times in the vertical refresh cycle. IBM PC compatible variants of NEC µPD7220 are using ISA bus. Variants Variants included: Intel licensed the design and called it the 82720 graphics display controller. Announced in 1982, it was the first of what would become a long line of Intel graphics processing units. East Germany (the German Democratic Republic) produced a replica designated U82720, used with the U880 replica of the Zilog Z80. The faster complementary metal–oxide–semiconductor (CMOS) variant was given the