## Display Device Driver Reference for OS/2

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### Strategy 2 - Add new definitions to the Shadow Registers

Another strategy is to add definitions to the shadow registers and bit-map header definition to support the new chip set, but leave the XGA and 8514 definitions in place. This has the advantage of allowing the values in the shadow registers to be written directly to hardware. The disadvantage is that much of the setup code for BitBlt, line drawing, and so forth, will have to be changed to accommodate these new register definitions. This strategy will be time-consuming and error-prone.