Operating Systems And Software Utilities

Published Date: 02 Nov 2017

Hardware functions and communication between different pieces of hardware, management functions of operative systems, comparison of operative systems, software utilities and their effect on performance.

Table of Contents

Hardware

In this section I will be using a lot of block diagrams, these help understand and visualize the components beforehand. So, let’s start with one to provide a general overview of a computer. The hardware noted will be the main topics we will be talking about in this section. Image the large box as the computer case.

Power supply unit

Drives such as CD/DVD drives and HDDS

Motherboard

CPU Slot

Back Panel Connectors

PCI Adapter Slots

Northbridge

Southbridge

RAM Slots

Connec-tors

BIOS

As we can see there are a lot of things going on in this diagram, especially on the motherboard but in reality this is a very much simplified diagram. These components will connect via cables; the motherboard has a lot of connections within it in order for everything to communicate, then there are peripherals for the user to communicate with this environment and probably other many other connections which we could spend years talking about. The main thing to understand from this diagram is that the motherboard is at the heart of all these operations, everything seems to either connect to it or be on it. The power supply supplies power to all components of the computer, in our simplified diagram it would connect to the motherboard and to our drives, it may also connect to other hardware in our PCI adapter slot. The drives would connect to our motherboard connectors, the CPU would go in the CPU slot, our RAM would go in the RAM slots and any expansion cards in the PCI adapter slots (for example graphics cards and sound cards). Any peripherals would then connect to the back panel connectors on the motherboard or to any slots on the case, the slots on the case would have to connect to the motherboard, as would the power button.

Power Supply Unit (PSU)

This is probably the easiest component to describe as it does exactly what the name tells us, supplies power! To do this it converts power from the mains into a lower voltage power in order for it to be useable by the internal components of the computer (usually using a switching regulator). Most PSU’s comply with the ATX standard making it suitable for most motherboards.

Basic input/output system (BIOS)

BIOS is simply software, but very important software! Stored in non-volatile read-only flash memory which is located directly on the motherboard, the BIOS has many important functions, one of those being loading the operative system. When your computer first boots up there needs to be something to send instructions to the microprocessor about what to do, the processor needs to load the OS but the OS is stored somewhere else, it also needs to execute certain checks on the power and hardware, load drivers, setting and all these other things to make sure the computer is ready for boot up and this is where the BIOS comes in by telling the microprocessor exactly what to do.

Central Processing Unit (CPU)

Register

Control Unit

Program counter

Memory Management

Cache

ALU

Bus Interface Unit

The diagram on the left represents a single CPU with its basic components: the arithmetical/logical unit (ALU), the control unit (CU), the registers, cache and the I/O (input/output) unit. In this section of the report I will briefly explain the functions of these components and how it all works together. For all this to make sense we need to first outline that the CPU is the "brain" of the computer, at a very basic level it processes information sent into it via the I/O unit and sends it back using the same unit. In order to understand how the CPU works we must first understand what each component does and with that some understanding of how it all goes together should follow.

A good starting point is the control unit. It controls and deciphers the instructions to be executed using the fetch-execute cycle (more on this later); usually it gets instructions from memory and then this is followed by moving data or addresses between different parts of the CPU. This is also where the program counter and memory management unit are located; the program counter contains either the address of the current instruction or that of the instruction to be executed and it is crucial to the above described process because it enables the CU to determine which instructions should be executed and the memory management unit controls the fetching of data and instructions from memory. Another part of the CU is the I/O unit or sometimes the Bus Interface Unit (the BIU combines I/O in one channel), the I/O unit is responsible for the input and output of information to and from the CPU, when data is sent to the CPU (usually from RAM) it has a higher current than that of the CPU, the CPU has very delicate parts which can’t handle this current and therefore the I/O unit will pass this data through a buffer which will bring the current back to something the CPU can work with. The opposite process will happen with data leaving the processor.

The arithmetical/logical unit is where arithmetical/logical calculations take place and data is temporarily stored, so from the control unit instructions go to the AUI to be calculated and modified according to the instructions. Registers hold data in order for it to be accessed and manipulated very quickly by the ALU, this date is taken from memory and stored here temporarily, once this data gets manipulated by instructions it might go back into main memory but a copy of it may be held in the registers, now when I say data I mean integer or floating point values, not data as we are used to talking about it, this memory is volatile.

Finally the last component is cache, there are most commonly 3 level of cache (L1, L2 and L3) and cache is a small amount of memory, larger than registers, which can be accessed very fast by the control unit. It reduces the time taken to access memory which is frequently used by holding it, when the control unit needs to write into memory instead of checking the main memory directly, it will first check L1 cache and if it’s there the control unit will write into it very fast, otherwise it will find the next level of cache and repeat the process. When the last level of cache has been checked if the memory address isn’t found then it will go through the bus interface unit to retrieve the location from main memory and write into it.

Management Functions of Operative Systems

Machine Management

Machine managements is probably the most important function of an operative system, when you turn your computer on you probably have a lot of applications opening and closing but whilst you are using your computer, even more so! These applications require CPU power, memory, I/O bandwidth and other things, the OS has to somehow manage which applications will get the resources first and try to make sure all applications get what they need by prioritizing what needs to be done first.

User Interface

The operative system provides the means for the user to interact with the computer, most popularly the development here is in tern of a graphical user interface which allows the users to control the system whilst visualizing what they are doing. Without the UI (user interface) it would be extremely complicated to interact with the system and even without the graphical interface it is rather complicated as we can see by using MS DOS which uses command lines.

Peripheral Management

An operative system on top of managing the machine itself also needs to manage any peripherals connected to it, these peripherals include things such as printers, scanners, monitors and other devices connected to the computer. These peripherals have been programmed in such a way that they will work with the operative system for example you can change the resolution of your monitor , the layout of your keyboard, the way the mouse works and manage the files on a PEN drive all using your OS.

File Management

File management is another crucial function of operative systems, operative systems allow you to store personal files in your secondary storage devices (HDD’s and SSD’s), you can create folders, and manage these files and where they are located using the operative system.

Security

Operative systems need to provide security to the system itself as well as the user’s data and account. It protects user data by encrypting hard drives and password protecting user accounts and it also has certain tools which protect your machine from unauthorized access, most of these tools within the operative system itself are rather basic and easily bypassed sometimes.

Task Management

Operative systems must manage tasks (see them through from start to finish) and allow the user to in some way be involved in this as the user should know what is happening on their computer. It must also know how much disk, CPU and memory usages the particular task requires, and possibly plan how much it will need to use in order to prepare for it. Together with system management the OS will prepare the system for this task and see the whole process through.

MS DOS and Windows 8

MS DOS

MS DOS uses command lines and therefore it doesn’t have a lot going for it in features or functions, the users had to insert command lines into the OS which mostly consisted of manipulation of files and navigation, any other task were handled by programs which could only run one at a time due to small amounts of RAM with the exception of Terminate and Stay Resident (TSR) programs which could stay in memory but these crashed a lot due to overlaps in memory. So to sum up, in terms of machine management, there is usually only one program running, if a TSR program is running as well chance is it will crash when an overlap in memory occurs; the user interface is text and command lines therefore the user still knows what he is doing at most times; there is actually a device manager for MS-DOS which has to be installed but it is very limited and only a small selection of devices can be handled; through command lines you could manage the files stored in your system, you would however need to know the name of the file you wanted to manage to locate it as there is no way of simply searching using the GUI (due to it not existing); strange as it might be there wasn’t really such a thing as a need for security in MS DOS, the telephone dial up links were awfully slow and the personal computer wasn’t something readily available, all applications on the computer were able to access everything on that computer but at the time this wasn’t much of an issue; finally task management, there wasn’t a need for it as all tasks were methodical from start to end and there was no such a thing as multi-tasking apart from the previously stated TSR programs. These are the features and functions of MS DOS, although now the ability to manage your personal files and multi-tasking are things we take for granted, back then command lines and TSR programs were as good as it got.

Windows 8

Windows 8 is now the newest OS available from Microsoft © and it has come a long way since MS DOS mainly by the addition of a graphical user interface, this operative system allows you to manipulate your files, choose where they are located, change their name to anything you want excluding certain special characters and do just about any imaginable thing with these files. True multi-tasking is also available; you can run many applications at the same time and prioritize the ones you want to be processed faster using the task manager; your OS is responsible for deciding which applications get what resource usage in a way that will try as much as possible not to make any of them crash. Computer architecture has come a long way and therefore RAM is very cheap and readily available, processors are faster and also cheaper; personal computers are now readily available with many people having even more than one personal computer. The concept of multiple people using the same computer has been abandoned and Windows 8 is definitely catering more towards the idea that people have more than one computer available to them however it is possible to set up other user accounts. A user isn’t able to easily access the personal files of one another user (apart from administrator/standard user set-ups in which