User guide

10
Section III
Principles of Operation
3-1 A3A4 Color Video Processor.
3-2 The A3A4 color video board uses a dual-access memory array. This allows
simultaneous use of the video memory by the 85662A data and control bus as
well as the color video processor (A3A4U2) that changes the video from
monochrome to color and formats the information into a compressed data stream.
3-3 For sweep times of ≤10 milliseconds (fast sweep), the A3A4 digitizes the fast
sweep data that comes in as analog-X and -Y signals. Since the fast sweep data is
now captured in digital format it has the added benefit of being able to be saved
and printed using the GPIB interface, just like the slower sweeps.
3-4 A1A21 Plotter.
3-5 The A1A21 plotter board converts the compressed data into a raster scan format
for driving the LCD.
3-6 A1A22 SRAM.
3-7 The SRAM board receives raster scan data and stores it in page switched static
RAM. Each page contains enough information to paint a full screen on the LCD.
There are two pages of static RAM. One page refreshes while the other page
paints to the LCD.