what is the three draw back of disk operating system?

Answer 1

First was RAM allocation. It could only directly access a total of 1024 kilobytes of RAM, a portion of that was pre-allocated in ways that were somewhat wasteful.

Second was disc drive size. This is a related issue to the RAM issue... the operating system couldn't understand beyond a 32 mb logical hard drive. You could "partition" a larger drive, but ran out of "drive letters" to assign to the partitions if you went past 256 sections.

Third is the ability to access the power of better processors. DOS was designed for the 8088 processor and worked well with the limited power of the PC's that used it. The 286 came along and the rules changed. By the time the 486 hit the market DOS was doomed.

Dos 3.0 was a very useful and stable operating system. Each upgrade after that allowed accessing the power of better machines, but compromised stability. Eventually with DOS 7.X as the "backbone" of Windows 95 DOS reached its limit of ability to be made to handle the power of modern machines.

Answer 2

How well it is accepted so you have a range of software

Stability - crashes and virus attacks

Hardware - does it include drivers for the hardware you need