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Graphics Display Hardware. Display technologies CRT LCD Storage tube Drawing methods Vector Raster Architecture. Sketchpad. 1962 @ MIT Light pen Powered by “Whirlwind”, MIT’s prototype of the 1 st interactive computer Req’d high bandwidth Vector display Monochromatic.
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Graphics Display Hardware • Display technologies • CRT • LCD • Storage tube • Drawing methods • Vector • Raster • Architecture CS-321Dr. Mark L. Hornick
Sketchpad • 1962 @ MIT • Light pen • Powered by “Whirlwind”, MIT’s prototype of the 1st interactive computer • Req’d high bandwidth • Vector display • Monochromatic CS-321Dr. Mark L. Hornick
“Modern” Cathode Ray Tube (CRT) Quasi-spherical screen Phosphorescence period = 1/30 s to 1/60 s CS-321Dr. Mark L. Hornick
CRT – Sony Trinitron • Slotted shadow mask • Curvilinear screen • Larger holes -- brighter image CS-321Dr. Mark L. Hornick
Vector Scanning • Electron beam can be arbitrarily directed • Number of displayable vectors is finite • Non-standard drive electronics CS-321Dr. Mark L. Hornick
Early hi-performance displays Display Processor 1200-9600 baud serial Minicomputer • Begin • COLOR(a)MOVE(ix,iy)DRAW(ix,iy)COLOR(b)DRAW(…) • End CS-321Dr. Mark L. Hornick
TektronixVector Display • T4010 • 512 x 512 • ~$8,000 • T4014 • 4096 x 3172 • ~$18,000 • PersistentStorage Phosphor • No digital memory CS-321Dr. Mark L. Hornick
Direct View Storage Tube • Two electron guns • Primary electron gun draws the picture by knocking out electrons from the storage grid, producing a positively charged pattern. • Low speed electrons from the flood gun are attracted to the storage grid, and pass through the positively charge pattern spots (past the collector grid) to hit the screen. • Once a picture is drawn it stays until erased by putting a charge over all of the storage grid so that the electrons hit all of the screen (producing a green flash on a green screen monitor). • Much cheaper then a regular random scan system • did not require a built in CPU • host computer was used to draw the image once CS-321Dr. Mark L. Hornick
1200-9600 baud serial MOVE(ix,iy)DRAW(ix,iy)POINT(ix,iy)DASH(ix,iy,idash) CS-321Dr. Mark L. Hornick
Circa 1981 CS-321Dr. Mark L. Hornick
Raster Scanning CS-321Dr. Mark L. Hornick
Video Display Video graphics adapter Television monitor CS-321Dr. Mark L. Hornick
Early graphics adapters Frame buffer CPU SystemMemory Scan Converter video, vga Pixel construction Bus • CPU constructs “virtual image” in System Memory • Scan converter reads virtual image and converts to video or vga signals CS-321Dr. Mark L. Hornick