What is assembly language? Explain the assembler directives?

It is sometimes referred to as assembly or ASL, assembly language is a low-level programming language used to interface with computer hardware. Assembly language uses structured commands as substitutions for numbers allowing humans to read the code easier than looking at binary. [...]

What is SCSI bus? Explain main phases involved in the operation of the SCSI bus.

SCSI is an acronym for Small Computer Systems Interface. It is an ANSI standard that has become one of the leading I/O buses in the computer industry. The foundation of the SCSI standard was laid by Shugart Associates (the same guys that gave the world the first mini floppy disks) when they introduced the SASI bus (Shugart Associates Standard Interface). [...]