Q: What type of graphics does it have?
First of all, not all Rainbow 100s have graphics capability. The graphics option is contained on a daughter board shipped with some Rainbows.
The Rainbow's graphics card was very advanced in its time. It had a maximum resolution of 800 by 220 with 2 planes. The Rainbow can display up to four unique colors in this mode chosen from a palette of 4096 colors. In medium resolution mode, the maximum resolution was 384 by 220 pixels with 4 planes. The Rainbow could display up to 16 unique colors from a palette of 4096 colors. Due to the design of the Rainbow 100A model, the palette is reduced to 1024 on the earlier machines.
The graphics card also had additional features, including smooth horizontal and vertical scrolling, a pattern generator/multiplier, and read-back ability. The pattern generator/multiplier was capable of tiling and providing textures for graphics and lines. The read- back feature allowed the computer to read the current planes shown back into memory, mainly for diagnostic purposes.
Many complained about how difficult it was to program the hardware. The card contained hardware-level line drawing functions and other graphics primitives that were only present later in graphics accelerators on PC for CAD and later, for Windows. However, unlike the PC, graphics RAM is not mapped to the system memory map; the transfer of bytes into graphics RAM on a Rainbow is more complicated, requiring specialized interrupt calls. The distinct separation of the graphics RAM from the main memory map makes the direct transfer of bytes slower and more difficult than accessing graphics RAM on an IBM PC.
To test for the graphics option, one can either look physically or use software to check. After removing the motherboard, the graphics option should be a daughter board located at the rear right side of the board. Also, one can use the program OPTION, which tests your Rainbow for various hardware options installed.