MC9224 - System Software - Question Bank
Unit - 1
1) What
is system software?
System software consists of variety of programs that supports the
operations of a computer. This makes it possible for the user to focus on an
application or other problem to be solved ,without needing to know the details
of how the machine works internally.
Examples of system software are text-editors,compilers,loaders or linkers,debuggers,assemblers,and
operating systems.
2)
How
system software is different from Software?
The most important characteristic in which most system software
differ from application software is machine dependency.
An application program is primarily concerned with the solution to some
problem,using computer as a tool. The focus is on the application,not on the
application system.
System programs, on the other hand,are intended to support the operation
and use of the computer itself,rather than any particular application. They are
usually related to the architecture of the machine on which they are to run.
3) Explain
the machine dependency of system
software with examples?
An assembler is a system software. It translates mnemonic instructions
into machine code; the instruction formats,addressing modes ,etc,are of direct
concern in assembler design.
Similarly, compilers must generate machine language code,taking into
account such hardware characteristics as the number and the types of registers
and machine instructions available
Operating systems are directly concerned with the management of nearly
all of the resources of a computer system.
Ø Example:
Ø When you took the first programming
course
·
Text
editor - create and modify the program
·
Compiler-
translate programs into machine language
·
Loader
or linker - load machine language program into memory
Ø and
prepared for execution
·
Debugger -
help detect errors in the program
Ø When you wrote programs in
assembler language
·
Assembler -
translate assembly program into machine language
·
Macro
processor - translate macros instructions into its definition
Ø When you control all of these
processes
·
By interacting with the OS
4) What
are the important machine structures used in the design of system software?
Ø Memory structure
Ø Registers
Ø Data formats
Ø Instruction formats
Ø Addressing modes
Ø Instruction set
5) What is SIC machine?
SIC refers to Simplified Instruction Computer which is a hypothetical computer that has been
designed to include the hardware features
most often found on real machines,while avoiding unusual and irrelevant
complexities. This allows to clearly separate the central concepts of a system
software from the implementation details associated with a particular machine.
6)
Explain SIC
Machine architecture.
SIC Machine Architecture
Ø
Memory
o 215
bytes in the computer memory
o 3
consecutive bytes form a word
o 8-bit
bytes
Ø
Registers
Ø
Data Formats
o
Integers
are stored as 24-bit binary numbers; 2’s complement representation is used for
negative values
o
No
floating-point hardware
Ø
Instruction Formats
Ø
Addressing Modes
Ø
Instruction Set
o
integer arithmetic operations: ADD, SUB, MUL, DIV, etc.
§
All
arithmetic operations involve register A and a word in memory, with the result
being left in the register
o
comparison: COMP
§
COMP
compares the value in register A with a word in memory, this instruction sets a
condition code CC to indicate the result
o
conditional jump instructions: JLT, JEQ, JGT
§
these
instructions test the setting of CC and jump accordingly
o
subroutine linkage: JSUB, RSUB
§
JSUB
jumps to the subroutine, placing the return address in register L
§
RSUB
returns by jumping to the address contained in register L
Ø
Input and Output
o
Input
and output are performed by transferring 1 byte at a time to or from the
rightmost 8 bits of register A
o
The Test
Device (TD) instruction tests whether the addressed device is ready to send or
receive a byte of data
o
Read
Data (RD)
o
Write
Data (WD)
7)
What are the
contents of status word register?
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