NEC µPD7220

The High-Performance Graphics Display Controller 7220 (commonly µPD7220 or NEC 7220) is a video interface controller capable of drawing lines, circles, arcs, and character graphics to a bit-mapped display. It was developed by NEC and used in NEC's APC III computers, the optional graphics module for the DEC Rainbow, the Tulip System-1, and the Epson QX-10.

The µPD7220 was one of the first implementations of a graphics display controller as a single Large Scale Integration (LSI) integrated circuit chip, enabling the design of low-cost, high-performance video graphics cards such as those from Number Nine Visual Technology. It became one of the best known of what were known as graphics processing units in the 1980s.

Details

The 7220 was announced by NEC Information Systems, the US arm of the Nippon Electric Company (now NEC) in 1982. The project was started in 1979, and a paper was published in 1981. By 1983, it was used in early computers from NEC itself, and others from Digital Equipment Corporation and Wang Laboratories. A year after 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.

NEC

NEC Corporation (日本電気株式会社, Nippon Denki Kabushiki Gaisha) is a Japanese multinational provider of information technology (IT) services and products, with its headquarters in Minato, Tokyo, Japan. NEC provides IT and network solutions to business enterprises, communications services providers and to government agencies, and has also been the biggest PC vendor in Japan since the 1980s. The company was known as the Nippon Electric Company, Limited, before rebranding in 1983 as just NEC. Its NEC Semiconductors business unit was one of the worldwide top 20 semiconductor sales leaders before merging with Renesas Electronics. NEC is a member of the Sumitomo Group.

History

1898 to 1919

Kunihiko Iwadare and Takeshiro Maeda established Nippon Electric Limited Partnership on August 31, 1898 by using facilities that they had bought from Miyoshi Electrical Manufacturing Company. Iwadare acted as the representative partner; Maeda handled company sales. Western Electric, which had an interest in the Japanese phone market, was represented by Walter Tenney Carleton. Carleton was also responsible for the renovation of the Miyoshi facilities. It was agreed that the partnership would be reorganized as a joint-stock company when treaty would allow it. On July 17, 1899 the revised treaty between Japan and the United States went into effect. Nippon Electric Company, Limited was organized the same day with Western Electric Company to become the first Japanese joint-venture with foreign capital. Iwadare was named managing director. Ernest Clement and Carleton were named as directors. Maeda and Mototeru Fujii were assigned to be auditors. Iwadare, Maeda and Carleton handled the overall management.

Floppy-disk controller

A floppy-disk controller (FDC) is a special-purpose chip and associated disk controller circuitry that directs and controls reading from and writing to a computer's floppy disk drive (FDD). This article contains concepts common to FDCs based on the NEC µPD765 and Intel 8272A or 82072A and their descendants, as used in the IBM PC and compatibles from the 1980s and 1990s. The concepts may or may not be applicable to, or illustrative of, other controllers or architectures.

Overview

A single floppy-disc controller (FDC) board can support up to four floppy disk drives. The controller is linked to the system bus of the computer and appears as a set of I/O ports to the CPU. It is often also connected to a channel of the DMA controller. On the x86 PC the floppy controller uses IRQ 6, on other systems other interrupt schemes may be used. The floppy disc controller usually performs data transmission in direct memory access (DMA) mode.

The diagram below shows a floppy disc controller which communicates with the CPU via an Industry Standard Architecture (ISA) bus. An alternative arrangement which is more usual in recent designs has the FDC included in a super I/O chip which communicates via a Low Pin Count (LPC) bus.

Numerical Electromagnetics Code

The Numerical Electromagnetics Code, or NEC, is a popular antenna modeling system for wire and surface antennas. It was originally written in FORTRAN in the 1970s by Gerald Burke and Andrew Poggio of the Lawrence Livermore National Laboratory. The code was made publicly available for general use and has subsequently been distributed for many computer platforms from mainframes to PCs.

NEC is widely used for modelling antenna designs, particularly for common designs like television and radio antennas, shortwave and ham radio, and similar examples. Examples of practically any common antenna type can be found in NEC format on the internet. While highly adaptable, NEC has its limits, and other systems are commonly used for very large or complex antennas, or special cases like microwave antennas.

By far the most common version is NEC-2, the last to be released in fully public form. There is a wide and varied market of applications that embed the NEC-2 code within frameworks to simplify or automate common tasks. Later versions, NEC-3 and NEC-4, are freely available as compiled binaries but have not been nearly as popular.