The following exercises must be compiled and run in real-address mode. Be sure t

Question

The following exercises must be compiled and run in real-address mode. Be sure to make a backup
copy of any disk affected by these programs, or create a temporary scratch disk to be used while testing
them. Under no circumstances should you run the programs on a fixed disk until you have
debugged them carefully!

This must be written in masm assembly.

1. Set Default Disk Drive
Write a procedure that prompts the user for a disk drive letter (A, B, C, or D), and then sets the default
drive to the user’s choice.

Explanation / Answer

When hard drives got to be distinctly modest, the "costly" PCs ordinarily had two floppy drives (one to boot and run normal projects, one to spare information and run particular projects). Thus it was regular for the motherboard equipment to bolster two floppy drives at settled framework addresses. Since it was incorporated with the equipment, it was suspected that building a similar necessity into the OS was adequate, and any hard drives added to the machine would begin with circle C: et cetera.

Amid the move from 5.25" plates (which were really, physically floppy) to 3.5" circles (which were encased in a harder plastic shell) it was regular to have both drives in one framework, and again it was upheld on the motherboard with equipment, and in the OS at settled locations. As not very many frameworks came up short on drive letters, it was not thought to be vital to consider making those drives re-assignable in the OS until much later when drives were disconnected alongside locations due to the plug'n'play standard.

A ton of programming was created since that time, and tragically quite a bit of it anticipated that would see long haul stockpiling on the C: drive. This incorporates the BIOS programming that boots the PC. You can even now join two floppy drives, boot into DOS 6.1, and utilize it as you would have in the mid 90's, with floppy drives An: and B:.

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