Author: Neftaly Malatjie

The programme methodology includes facilitator presentations, readings, individual activities, group discussions, and skill application exercises.

When a hardware device needs the CPU to do something—for instance, when the keyboard needs the CPU to process a keystroke after a key has been pressed—the device needs a way to get the CPU’s attention, and the CPU must know what to do once it turns its attention to the device. These interruptions to the CPU are called hardware interrupts, and the device initiates an interrupt by placing voltage on the designated IRQ (interrupt request) line assigned to it. This voltage on the line serves as a signal to the CPU that the device has a request that needs processing. Often, a hardware device that needs attention from the CPU is referred to as “needing servicing.” Interrupts initiate many processes that the CPU carries out, and these processes are said to be “interrupt-driven.”

TESTS MUST BE CONDUCTED TO VERIFY ALL SYSTEM SOFTWARE COMMUNICATES WITH HARDWARE AND OTHER APPLICATION SOFTWARE

The interaction between the software and the hardware must be tested. Every software has drivers. Device drivers are software designed to interface with specific hardware devices. They are stored on the hard drive and installed when the OS is first installed or when new hardware is added to a system. The OS provides some device drivers, and the manufacturer of the specific hardware device with which they are designed to interface provides others. In either case, unlike BIOS, device drivers are usually written for a particular OS and might need to be rewritten for use with another.

In addition, there are also system resources. A system resource is a tool used by either hardware or software to communicate with the other. When BIOS or a driver wants to send data to a device (such as when you save a file to the hard drive), or when the device needs attention (such as when you press a key on the keyboard), the device or software uses system resources to communicate. There are four types of system resources: memory addresses, I/O addresses, interrupt request numbers (IRQs), and direct memory access (DMA) channels.

As Table explains, all four resources are used for communication between hardware and software. Hardware devices signal the CPU for attention using an IRQ. Software addresses a device by one of its I/O addresses. Software looks at memory as a hardware device and addresses it with memory addresses, and DMA channels pass data back and forth between a hardware device and memory. All four system resources depend on certain lines on a bus on the motherboard. A bus such as the system bus has three components: the data bus carries data, the address bus communicates addresses (both memory addresses and I/O addresses), and the control bus controls communication (IRQs and DMA channels are controlled by this portion of the bus). Let’s turn our attention to a more detailed description of the four resources and how they work.

As a computer technician, once you have installed system and application software, you need to test that they work properly before you let the user start working on the computer. Before you start testing the installations, you need to make sure that;

• The computer has rebooted after the software installation.
• The new operating system has started
• All applications have been installed

Once these operations and tasks have been completed, you need to check the computer logs to ensure errors are not occurring. Logs are records of events that have happened recently.

The device manager can be used to view the layout of all the hardware that you installed. This is illustrated below. The device manager shows you if there are any problems with any specific device or any device is missing;

If you want to view the logs of problems that are not serious enough to make installation fail, but might cause problems in the future, you use the event viewer in windows. This is shown below;

In addition to the Windows tools, you can buy commercial system analysis tools that help you to make sure that the system is performing well. Applications also have a User’s guide or Help that usually lists the types of errors and problems that may occur when you use them.

In addition, applications also often have readme file. The readme file, as its name suggests, asks you to read about the application. It often gives you information about the installation process.

Even if you are an experienced computer user, you should go through the applications you have installed when you have finished installing them. You should check that all the functions work as you go through the application. This will help you to test the installation.

Burn-in-testing is another way of testing the installation. Burn-in may be conducted to ensure that a device or system functions properly before it leaves the manufacturing plant or may be part of a repair or maintenance routine. 

An end user may use a burn-in process to ensure that new equipment is functioning properly, for example, running a new computer for several days before committing it to serious use. If any of the components are defective the problem will usually show up within this initial testing time frame.

When a faulty device or system is brought into a repair facility, the malfunction might not occur until the hardware has been warmed or cooled to a certain temperature. Humidity may also be a factor. Under these circumstances, a burn-in must be performed and environmental parameters varied until the problem is found. The equipment is powered-up and then left to run continuously for hours (or sometimes for days) until the malfunction is observed and can be diagnosed.

The term burn-in is sometimes used in reference to a phenomenon in which faint, permanent “ghosts” appear on video displays that have displayed fixed images for long periods of time. This problem is also known as screen burn or phosphor burn. In older cathode-ray-tube (CRT) displays, screen savers were used to prevent burn-in. Newer computer displays rarely exhibit burn-in except under extreme conditions. However, burn-in remains a potential problem with large-screen video displays such as those found in home theatre systems.

The goal of your application testing is to verify that everything that works on your current platform also works on your current version of Windows. If an application was written for an earlier version of Windows, it does not necessarily use new Windows features, but its functionality should work in Windows 2000 as it does on your current platform.