Hercules Graphics Card

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A Hercules Graphics card.

The Hercules Graphics Card (HGC) is a piece of hardware which gives IBM personal computers display capabilities superior than their default hardware. The card was developed in 1982 by Van Suwannukul who wanted to be able to display the Thai alphabet on a computer which wasn't possible at lower resolutions or using the stock IBM Monochrome Display Adapter.

The Hercules Graphics Card can operate in two different modes, text mode and graphics mode. In text mode, the card is compatible with the IBM Monochrome Display Adapter. It supports 80x25 characters on the screen. Each character is 9x14 pixels, but only the center 7x11 are used for a character. The total screen resolution is 720x350, but you cannot modify the screen at the pixel level, only the character level. On a standard 4:3 ratio monitor, the pixel ratio is 1:1.55.

In graphics mode, every pixel on the screen is independently addressable allowing for more complex graphics. The resolution is 720x348 (two pixels are lost since the dimensions must be divisible by four for technical reasons). The pixel ratio is again 1:1.55 on a standard 4:3 display.

Actual Data Simulated Monitor
Space Quest II - Vohaul's Revenge - Screenshot - Vohaul - Hercules.png Hercules - Screenshot - Space Quest II - Simulated Monitor.png

By the time my family bought our first computer, the VGA standard was already popular. I think I only ever saw Hercules graphics once on a computer at my step-father's office, but I never used it. It wasn't until DOSBox started emulating it that I became more familiar with the display.

Software

Hercules Graphics were not nearly as popular as CGA graphics which came out a year earlier, but it did support a resolution almost twice the size of CGA's color mode, and larger than CGA's monochrome mode. However, few developers drew completely new graphics for HGC, and usually used a driver to scale up their color graphics and convert them to dithered black and white. Here are some screenshots of Hercules graphics for popular games.

Links

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