Fully Integrated EDI: Fully integrated EDI systems encompass electronic data sharing throughout all aspects of the purchasing and payments cycle. The fully integrated EDI system allows the purchasers computer system to electronically check inventory levels and production schedules to determine whether the requested item in stock or when it scheduled to be produced.
Financial EDI: The banker EDI council defines financial EDI as the electronic exchange of payments related information or financially related documents in standard formats between partners. Financially EDI is the key distinguishing feature between partially and fully integrated EDI systems. Some farms may transfer funds electronically and produce the remittance advice in hard copy format that is sent through the postal service.
In a client/ server application there are two major classes of Software:
Client Software:
Client Software usually residing on an end users desktop and providing navigation and display.
Server Software:
Server Software usually residing on a workstation or server class machine and providing backend data access services( where the data can be something simple like file or complex like a relational database). As an example: E-mail- the protocol is simple mail transport protocol and its purpose is allows the transmission of text message and binary attachments across the internet technology. Another one is Chat and its protocol name is internet relay chat protocol, it provides away by one user to talk to one another in real time over the internet. The real time chat groups are called channels.
Computer criminals are mean and sinister types. But many more wear business suits have university degrees, and appear to be pillars of their communities. Some are high schools or university students. Others are middle aged business executives. Some are mentally deranged, overtly hostile or extremely committed to a cause and they attack computers as a symbol.
Whatever their characteristics and motivations computer criminals have access to enormous amounts of hardware, software and data; they have the potential to cripple much of effective business and government throughout the world. In a sense then the purpose of computer security is to prevent these criminals from doing damage. Read More
Software is vulnerable to modifications that either cause it to fail or cause it to perform an unintended task. Indeed, because software is so susceptible to ‘off by one’ errors, it is quite easy to modify. Changing a bit or two can convert a working program into a failing one. Depending on which bit was changed, the program may crash when it begins, or it may execute for some time before it falters.
Other categories of software modification include:
A Trojan horse: A Trojan horse is a program that overtly does one thing while covertly doing another.
A Virus: A Virus is a specific type of Trojan horse that can be used to spread its ‘infection’ from one computer to another.
A Trapdoor: A Trapdoor is a program that has a secret entry point.
Information leaks: Information leaks in a program: code that makes information accessible to unauthorized people or programs.
When we prepare to test a system we usually try to imagine how the system can fail, then we look for ways in which the requirements, design, or code can enable such failures. In the same way when we prepare to specify, design, code, or test a secure system, we try to imagine the vulnerabilities that would prevent us from reaching one or more of our three security goals. It is sometimes easier to consider vulnerabilities as they apply to all three broad categories of system resources, rather than to start with the security goals themselves. Read More
We use the term security in many ways in our daily lives. A security system protects our house, warning the neighbors or the police if an unauthorized intruder tries to get in. Financial security involves a set of investments that are adequately funded: When we talk about computer security we mean that we are addressing three very important aspects of any computer related system- Confidentiality, integrity, and availability.
Confidentiality: It ensures that computer-related assets are accessed only by authorized parties. That is only those who should have access to something will actually get that access. By access we mean not only reading but also viewing, printing, or simply knowing that a particular asset exists. Confidentiality is sometimes called secrecy or privacy.
Integrity: It means that assets can be modified only by authorized parties or only in authorized ways. In this context modification includes writing, changing, changing status, deleting and creating.
Availability: Availability means that assets are accessible to authorized parties at appropriate times. In other words if some person or system has legitimate access to a particular set of objects, that access should not be prevented. For this reason availability is sometimes known by its opposite, denial of service.
When you test any computer system, one of your jobs is to imagine how the system could malfunction. Then you improve the systems design so that the system can with stand any of the problems you have identified. In the same way, we analyze a system from a security perspective thinking about ways in which the systems security can malfunction and the value of its assets. Read More
An intruder must be expected to use any available means of penetration. The penetration may not necessary be by the most obvious means nor is it necessarily the one against which the most solid defense has been in stalled. This principle implies that computer security specialists must consider all possible means of penetration.
Moreover the penetration analysis must be done repeatedly and especially whenever the system and its security change. Strengthening one aspect of a system may simply make another means of penetration more appealing to intruders.
The technique used to find the starting address of the service routine (commonly known as the interrupt address vector) varies from one microprocessor to another. With some microprocessors the manufactures define the fixed starting address for each interrupt. Other manufacturers use an indirect approach by defining fixed locations where the interrupt address vector is stored. Read More
The general characteristics of I/O are described effectively in this post. One communications with a microcomputer system via the I/O devices interfaced to it. The user can enter programs and data using the keyboard on a terminal and execute the programs to obtain results. Therefore the I/O devices connected to a microcomputer system provide an efficient means of communication between the computer and the outside world. In a typical microcomputer system the user gets involved with two types of I/O devices physical I/O and logical I/O. when the microcomputer has no operating system the user must work directly with physical I/O devices and perform details I/O design. Read More
The performance of a microcomputer system can be significantly improved by introducing a small expensive but fast memory between the microprocessor and main memory. This memory is called cache memory and this idea was first introduced in the IBM 360/85 computer. Later on this concept was also implemented in minicomputers such as PDP-11/70 with the advent of VLSI technology, the cache memory technique is gaining acceptance in the microprocessor world.
The relationship between the cache and main memory blocks is established using mapping techniques. Three widely used mapping techniques are
Direct mapping
Fully associative mapping
Set associative mapping
In the direct mapping the main memory address is divided into two fields an index field and a tag field. The number of bits in the index field is equal to the number of address bits required to access the cache memory. There are two ways of writing into cache the write back and write through methods, in the write back method whenever the microprocessor writes some things into a cache word a thirty bit is assigned to the cache word.
A memory unit is an internal part of any microcomputer system and its primary purpose is to hold programs and data. In a board sense a microcomputer memory system can be logically divided into three groups.
Processor Memory
Primary or Main memory
Secondary Memory
Processor memory refers to the microprocessor registers. These registers are used to hold temporary results when a computation is in progress. Also there is no speed disparity between these register and the microprocessor because they are fabricated using the same technology.
Primary or main memory is the storage area in which all programs are executed. The microprocessor can directly access only those items that are stored in primary memory.
Secondary memory refers to the storage medium comprising slow device such as magnetic tapes and disks. These devices are used to hold large data files and huge programs such as compilers and data base management systems which are not needed by the processor frequently. Secondary memory stores programs and data in excess of the main memory. There are two types of optical disks.
These are the CD ROM and the WORM. The CD ROM is inexpensive compared to the WORM drive. Hard disk memory is also frequently used with microcomputer systems. The hard disk also known as the fixed disk is not removable like the floppy disk.
