SEPARATE ALPHAis the opposite ofMERGE ALPHA WITH GRAPHICS. When separate, one or more bit plane is reserved for alpha text and the remaining planes are reserved for graphic output. The alpha and graphic planes can then be turned on or off orDUMPed independently. However,ALPHAtext color and graphic pens are limited as shown in the table below.
The following table shows the colors available whenSEPARATE ALPHA FROM GRAPHICSis used, depending on the total number of colors available.
Total Colors
Graph Pens
Black Alpha
White Alpha
Brown Alpha
Cyan Alpha
16
0-7
0
8
-
-
256
0-63
0
64
128
192
Porting Issues
HP BASIC assigns green to the first pen; HTBasic assigns white. If you prefer green or some other color, you must explicitly set a range of pen values to the color desired. The range starts with the white alpha pen value from the table above and continues to one less than the value of the brown alpha pen value. For 16 color systems, the last value should be 15. For example, the following code changes the alpha pen from white to green on a 16 color display:
