The Hercules Graphics Card (HGC) was a computer graphics controller made by Hercules Computer Technology, Inc. which, through its popularity, became a widely supported display standard. It was common on IBM PC compatibles connected to a monochrome monitor (green, amber, or page white). It supported one high resolution text mode and a single graphics mode. In 1984 its list price was USD 499 although it was often sold for less than the manufacturer's suggested price. 
Its provision of an MDA compatible high quality text mode in combination with a (for its time) high resolution graphics mode (as well as aggressive pricing) made the Hercules card extraordinarily popular in the early days of the PC. The existence of CGA emulation drivers/TSRs, which allowed Hercules users to run programs written for the CGA card's standard graphics modes (albeit only in monochrome, without actual color), may also have been a contributing factor to its success. Programming for the Hercules card's native graphics mode was somewhat hindered by a lack of BIOS support and standardization from IBM — after all, the HGC was a competing technology. Popular IBM PC programs at the time (such as Lotus 1-2-3 spreadsheet and Autocad computer-aided drafting) came with their own drivers to allow use of the Hercules graphics mode.
Long after its prime, the Hercules card continued to be popular for dual-monitor setups alongside another (colour) graphics adaptor. Certain software detected the HGC and used the monochrome display for extra data display while running the application on the other screen—for example a CAD work area would be displayed on the main (non-Hercules driven) screen and a list of drawing commands would be shown on the HGC driven monochrome screen. Some software debuggers could take advantage of an HGC to run the main program on the colour monitor and the debugger on the HGC.
The Hercules was developed in 1982 by Van Suwannukul, founder of Hercules Computer Technology. The system was created by Suwannukul initially so that he could work on his doctoral thesis on an IBM PC using the Thai alphabet (his native language).
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