IntroductionWhether you're planning to build your own computer or you simply would like to know more about how computers of old and new work then this page is for you. First let me start by pointing out a strange occurrence that has risen with regards to the term 'PC' which means 'Personal Computer.' Actually, thanks to Microsoft, when most people use the term PC they don't just mean a personal computer but also, a computer that uses a version of Microsoft's Windows operating system (WIndows 98, Windows XP, and so on). I have used computers most of my life from back in the day of the microcomputers (for further information please see elsewhere on this page) that had just a built-in BASIC interpreter for programming to the more modern desktops and laptops running Windows 7, Linux and Mac OS X. So, like many others, I have seen computers progress from 8-bit, 1MHz, 1K RAM machines that could load programs from cassette tape right up to the present computers that are 32-bit (or 64-bit) running in the GHz's with multiple cores and with GB's of RAM, as well as hard drives able to store TB's of data. All of that may have made not much sense to you but the aim of this page is to teach how computers typically work which includes steps to make your own simple computer. The information on this page, I must mention, can also be applied to parts of a video game console.
Computer BasicsYou may wonder what is the most important part of a computer; the answer is debatable. The CPU (Central Processing Unit, such as a Pentium) is the brains of the computer so without it the computer wouldn't start because there's no one to tell the other components what to do. But even if the CPU was installed but the PSU (Power Supply Unit) wasn't connected or working then nothing would happen if you tried to turn the computer on. Another very important part of a computer is the RAM (Random Access Memory), although the CPU has its own, tiny amount of internal RAM only a small amount of data can be stored there at one time so without the external RAM (external to the CPU) the computer wouldn't be able to do much. A CPU must have insructions, the start up code, ready for it as soon as the power is turned on; these startup instructions are stored in the BIOS (Basic Input/Output System) which is stored in a ROM (Read Only Memory) chip. The BIOS of modern computers can be changed, such as to update it to provide new features or to fix bugs, however, this opens up the possibility of a corrupted BIOS which would stop the computer from starting. The BIOS will check the system is running as it should and will display a limited amount of information about the hardware on screen, like how much RAM there is and if there are any errors. There will also be a setup configuration utility, usually accessed by pressing a certain button after power up, that allows the user to adjust settings such as the date and time, and what integrated devices should be enabled. When the BIOS is checking the hardware it runs what is known as its POST (Power-On Self Test) and will test the RAM and look for connected peripherals, namely floppy drive, harddrive, CD-ROM and the like. As soon as it has done that and there aren't any serious problems, the BIOS will load the operating system (e.g., Windows) from the harddrive (or other device). The operating system can't be loaded first since, even if there were no need for tests, code either in ROM or RAM has to be available as startup code to load data from a peripheral like a harddrive.
Anyone who has had keyboard troubles or pressed a key on the keyboard when a computer starts up will be faced with the puzzling error message that reports a keyboard error and asks the user to press any key to continue despite the keyboard not working. The keyboard always has been for most computers the one input device you need more than any other but still that's no excuse for that stupid error message. MicrocomputersPlease go to Microcomputers. Create Your Own ComputerPlease go to Create Your Own Computer
Repairs
One day your computer may be as fine as can be the next day it stops working or behaves oddly, especially if you have Windows as your operating system. The key to fixing the computer is first to work out if the fault or faults are because of a hardware or software problem, or even a combination of both.
Let me give you an example, I had an old desktop computer running Windows 98 SE that I had in addition to my main computer. Recently the Windows 98 computer would start up fine but after loading Windows or a few moments later the much feared blue screen would pop up, or sometimes the less serious explorer has performed an illegal operation error. A clue to what was wrong was that the errors were random and they had only started to appear recently.
Although software including drivers could be to blame, a dodgy power supply or faulty memory (RAM) were just as likely. I ruled out the PSU as it was of the type that is supposed to provide a power good signal to the motherboard that would prevent the computer from starting if the voltages were not a the right level. I also remembered that I had added extra memory recently so I removed the second DIMM memory stick. Now there were no errors, even after using the computer for some while just to make sure that removing the bad RAM really had caused so much trouble. Another example was when trying to install Windows 7 on a desktop PC; it would install fine until it got to the 'Completing installation' stage which is when it froze. I waited an hour and the computer was still stuck at the same point, so I had to shut down by holding the power button. From searching online I found many people had the same problem but there were numerous causes for the freezing. However, one of the suggestions worked, and that was to disable the on-board devices (LAN, audio, etc. but USB was fine to be left enabled which was just as well as the computer had no PS/2 ports) using the BIOS set-up facility (most commonly accessed by pressing the 'Del' key when the computer first starts up). The installation then went without a hitch and when I next restarted the computer I retuned to the BIOS set-up utility and re-enabled just one of the on-board devices. After Windows had loaded I then installed the driver, restarted and enabled another on-board device, and installed the driver and repeated those actions until all on-board devices were working. The reason for doing it one at a time was in case Windows had a problem with one of the on-board devices I would know it would be the most recent one I had enabled. Hard drives are still very common and have grown dramatically in capacity while dropping in price; 3TB hard drives are now available. Hard drives should last a long time which is just as well as for most computers they are the main form of storage and contain the operating system as well as personal files. But even modern hard drives can fail early on so you need to always make back-ups of valuable files on another storage device, such as a USB flash drive or external hard drive, another computer via a network connection, on CD or DVD, or online (but I would recommend local copies if possible and use online services as an extra form of back-up). If you do suspect a problem with your computer's hard drive, such as if you are getting file errors, stop using the computer and shut down. To test the hard drive you can use a boot CD or DVD which will run a number of tests on the hard drive or some BIOS set-up utilities have a built-in hard drive test. If you do find that the hard drive is about to fail there are a number of ways you can recover most or all of your files if you haven't already backed them up. One option is to use a Linux live CD or DVD which you can boot into, giving an operating system that runs just of the disc so there is no chance of effecting the hard drive. Using Linux you should be able to access the files on the hard drive and copy them over to another storage device like an external hard drive or USB flash drive. An alternative is to take the hard drive out of the computer after shutting it down and either put it into another computer or use a hard drive docking station. All content of this and related pages is copyright (c) James S. 2007-2012 | Added: Commodore VIC-20 Microcomputer Create Your Own Computer Introduction to Microcomputers Repairs.
You can email me at james.boshikoopa@gmail.com |