Different between IBM pc and IBM compatible in 5 points
Answers
Answer:
Explanation:
IBM PC was made by IBM. There were three major versions. The original IBM PC from 1981, PC/XT from 1983 and PC/AT from 1984. PC/XT had an option for hard disks, more memory and in general newer technology. The processor was same 4.77 MHz 8088. IBM PC/AT used 80286 processor originally at 6 MHz, later at 8 MHz.
Many manufacturers made their own MSDOS computers using same OS. However, as those were not hardware compatible with the IBM PC they could not run same programs apart from simple command line utilities. To solve this companies decided to make PCs that were almost perfect clones. Compact was the first one. There was nothing in the law to prevent copying the hardware. However, the BIOS code that was on the ROM was copyrighted. The clone manufacturers established a system of dirty and clean rooms. The dirty room analyzed the IBM PC code and wrote a report of it. The clean room wrote the BIOS on basis of it. Reports then went back and fort until the code was ready and tested. The people who wrote the code never saw the actual IBM PC BIOS code. For example the BIOS in some point had IBM PC copyright message. Some code tested the word IBM from it so the clone code could read for example: “Reserved for IBM compatibility” at the point. Sure the code could tell the difference if it wanted but program writers had no interest to artificially make the code less compatible. The more computers it could run the better.
The IBM PC clones often had better hardware than original IBM PC like using 8 MHz 8088 processors instead of the 4.77 MHz. They added real time clocks so that the y user did not need to enter the time and date at bootup (On PC/AT this was included) Modern PCs are direct descendants of the IBM PC compatible computers but to call them such would be strange.