Ultimate Compatibility When a company advertises a computer as being “IBM PC-compatible,” the best way to test its claim is to try to load an IBM release of PC-DOS, CP/M-86, or the UCSD p-system. I didn’t have the p-system, but I did have both PC-DOS and CP/M-86 and was able to try both of them on a prototype of the Compaq computer. The systems loaded and executed perfectly, with the exception of the BASIC on PC-DOS, which wouldn’t execute because the Compaq doesn’t have ROM BASIC. The BASICA provided on disk and all of the IBM PC sample BASIC programs found on the PC-DOS disk ran without incident. I also tried some CP/M-86 assembler-level software that I had written, and it worked without a hitch as well. I spent about an hour loading and running a number of game programs and some professional packages such as Wordstar and Supercalc. With one exception, they all worked correctly. The one that didn’t was a game program that ran perfectly but died when I tried to terminate the game. One of the programmers told me that the problem was probably a result of not initializing the hardware correctly when the system was powered up. The company assured me that the problem would be solved before any machines were shipped.