The Wrath of Manannan - King's Quest III Death Animation on Tandy/CGA/PCjr.

Channel:

Nerdly Pleasures

Subscribers:

711

Published on January 6, 2023 8:31:17 PM ● Video Link: https://www.youtube.com/watch?v=Xz1OrHzQIlw

Game:

King's Quest III (1986)

Duration: 1:34

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9

In this short video, I will demonstrate what happens in King's Quest III - To Heir is Human, if Gwydion is caught by Manannan trying to perform magic, collecting magical items or discovering the wizard's secrets on my Tandy 1000 TX. When Mannannan reduces you to ashes, the screen should shake. Sierra accomplished this differently with EGA, MCGA and VGA graphics than it did with CGA, Tandy 1000 and IBM PCjr. graphics.

CGA, Tandy 1000 and PCjr. use the Motorola 6845 CRT Controller chip or integrate it into their graphics hardware. This chip controls the video timings that these graphics adapters use and its registers can be used to affect the horizontal and vertical position of the active display area of the screen. When the Horizontal and Vertical Sync registers are written to rapidly the result is that the screen appears to shake. Some CGA/Tandy/PCjr games will allow the user to set the screen centering manually and when they do this they will write these registers. No emulator seems to support these registers, not DOSBox, not 86Box, so when playing the game with the Tandy, PCjr. or CGA graphics types, the screen will not shake.

EGA, MCGA and VGA implement some form of decreasingly compatible 6845 functionality in their hardware, but the horizontal and vertical sync registers do not work quite like the older adapters. These adapters support higher graphics resolutions and faster horizontal and vertical scan frequencies. Instead, games like KQ3 cause the screen to shake by rewriting the start address register in these adapters. DOSBox and other emulators support this method, so playing these games with EGA or VGA emulation options will make the shake work as expected.

As you may have noticed, I am using a composite capture device to capture the Tandy 1000 TX's video instead of capturing the RGBI output. This is because the composite capture device (Dazzle DVC-100) I sometimes use is more resilient to rapid sync changes than the RGB2HDMI (as captued by a Datapath VisionRGB E1s). RGB2HDMI will drop frames during the shaking, the Dazzle will not. Even though the colors may not be ideal and the image not as sharp as RGBI, King's Quest III and other AGI games remain very playable with Tandy or PCjr. composite. These adapters do not use artifact color, unlike CGA, with these games. They use direct color generated (effectively) at the 3.58MHz NTSC color carrier frequency.

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