Rockwell Automation 6000 Industrial Computers Technical Reference Guide - Manual (Page 5)

Video cards
A video interface takes digital information from the computer and converts it into video
signals that drive the computer display. The speed of the interface between the video
circuitry and processor influences the display’s update rates. Today’s most common
interfaces are based on either a PCI bus interface or the newer AGP (Advanced Graphics
Port) interface. The video interface can be either integrated into the motherboard or CPU
card, or located on a separate video card. Most of today’s computer motherboards have a
dedicated AGP slot.
The video interface uses very high-speed memory to storage the digital video
information. The amount of video memory required is a function of the display
resolution and color depth. For simple VGA (640x480 pixels) resolution and 256-bit (1
byte) color, only 307,200 bytes of video memory are needed. That is 1 byte for each
pixel. For XGA (1024x480 pixels) resolution and true 32-bit (4 byte) color, 3,145,728
bytes of video memory as required. This simple formula applies to typical computer
applications. Some newer video technologies such as 3D graphics require more memory.
Next-generation Intel processor chipsets will use system memory instead of traditional
video memory.
Allen-Bradley computers offer a variety of video interfaces. The 6181 computer and
6155 passive backplane computers have the video interface integrated into their CPU
cards. These interfaces currently support 1-2MB video memory and PCI interfaces. No
additional video card is required in these computers.
The 6155 active motherboard computer uses standard commercial video cards. The
current options are a 4MB PCI video card or an 8MB AGP video card.
The 6180 active motherboard computers use custom-designed PCI and AGP video cards.
The 6180 video cards are customized to provide internal connections to the integral LCD
display, as well as support external video connections. The current options are a 4MB
PCI video card or a 4MB AGP video card. The 4MB memory is sufficient to operate the
highest resolution display option (15” LCD, 1024x768) in true-color depth.
LCD Displays
The 6180 and 6181 computers have integrated LCD displays. These are either STN
(Super Twist Numatic) or TFT (Thin Film Transistor) color LCD displays. STN LCD
panels use a scanning type technology to control the liquid crystal pixels. The advantage
of STN is lower cost. The disadvantages are reduced brightness and contrast, reduced
viewing angles, and in some cases lower operating temperatures. TFT LCD panels use
individual transistors to control each pixel. The advantages of TFT are high brightness
and contrast, wide viewing angles, and higher operating temperatures. The disadvantage
of TFT is higher cost.
Current sizes offered in RAC6000 computers are 10.4” 640x480 resolution, 10.4”
800x600 resolution, 12.1” 800x600 resolution, and 15” 1024x768 resolution. LCD
displays differ from CRT displays, in that there is only 1 physical element for each