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COMPUTER BITS By JENNIFER BONNITCHA What to do when your computer goes bung; Pt.2 This is the second part of an on-going series about problems with personal computers and associated hardware. Since the type and number of computers, printers and various peripheral devices is enormous, the series will concentrate on some of the most common problems. In particular, we w·n cover some of the elements of the Central Processing Unit (CPU) (such as the power supply and motherboard), monitors, keyboards , printing devices and hard/floppy discs and their drives/controllers. We will also look at some software suggestions since hardware problems are often directly or indirectly linked to software problems. Of necessity this series, and in fact the entire column, tends to focus on the IBM and compatible market. The reason is simple. It is by far the most extensive and my experience is primarily with, but not exclusive to, this style of machine. I have been known to PIP with the best of them but sadly, in the business world, those days seem to have gone forever. Sure there are lots of happy Vegemites out there using home computers - they've been around much longer than the "traditional" PC. The problem is to keep as many people interested and happy as possible at the same time. You all know the line about pleasing all of the people some of the time and some of the people some of the time. Well in this instance, prepare yourself for the latter. Back to the task at hand, just 70 SILICON CHIP what can go wrong with your PC? Lots of things! The trouble is that for every problem you manage to solve, clever users find ways to keep coming up with new problems to tax their hardware and software - not to mention the grey matter of various technical support staff. Whenever you are presented with a problem, approach the task as logically as possible. Resist the urge to leap right in and tear the system apart. A cool, sensible approach is vital. Make notes as you go along, particularly if you need to change switch settings on the PCs, printers etc. Troubleshooting rules Basic problem determination involves several steps: (1). Check the installation and configuration. Make sure the correct cables are plugged into the right holes. Often on compatible PCs, the various outlets are not labelled. Additionally, you may have several add-on boards installed, each with similar-looking connections. (2). Check the installation and configuration of the software. Make sure that the correct printer, printer port, graphics board, monitor, mouse type, keyboard, etc has been selected. (3). If you still have a problem, work through the system bit by bit. Printer problems could stem from any number of components. Check that the cable is securely attached to both the PC and the printer. Make sure you are using the right cable. Make sure the printer is turned on and selected (no groaning please, sometimes the most obvious causes the greatest problem). (4). Check the simple, inexpensive things before the more complex and more expensive items. Change printer cables before trying another printer, for instance. (5). Check that the power supply does not suffer from interference, causing the computer to crash. If the screen image appears "wavy", move the monitor around. If the image improves, you could have power interference. (6). Read the manual. There is a reason for putting this as the last step. It is usually the last resort. Most people seem to have an inbuilt aversion to reading the manual. It's surprising how much information is contained within - and most of it is really good stuff if only you could make head or tail of it. Intermittent problems are by far the most irritating. Frustrating to the nth degree and difficult to duplicate, there is not much you can do unless a few simple steps are followed. Whenever possible, write down any messages from the computer, what happened immediately prior to the problem, and take a screen dump if possible (press either SHIFT PRTSC or the PRINT SCREEN key). Interpreting a user's description of what happened can be more difficult than actually solving the problem. Encourage the use of technically descriptive terms wherever possible so that each knows what the other is describing. In terms of failure rates, some items are more susceptible than others and notable amongst these are mechanical devices such as disc drives and power supplies. The irritating thing is that they sometimes fail with absolutely no warning. Memory devices can also fall into this category. Mean Time Between Failure (MTBF) is a rating expressed in thousands of hours. The figure given for computer devices is derived statistically from the results of tests carried out by the manufacturer. The device is subjected to various extremes of conditions in order to estimate how long the device can function before it fails mechanically. So in roughly "failure rate order" the following are most likely to cause you headaches: (1). Power supply; (2). Low level hard disc format; (3). Floppy disc drive; (4). Hard disc controller card; (5). Hard disc drive; (6). Memory chips. This series will examine all of the above. Remember that simple things can create the greatest problems. Running a computer all day while it sits at a nice sunny window (don't we wish!) can cause considerable overheating. This can lead tci premature aging of both mechanical and electronic components. If your computer is positioned in a corner where air doesn't circulate freely, you can also create overheating problems. Likewise with monitors covered in little bits of paper. It may look cute, but unless it is cooled efficiently, problems can develop. My computer won't work Sometimes you get a plaintive voice at the other end of the telephone, crying out for help. Many problems occur at boot time. During the Power On Self Test (POST) sequence, your computer takes itself through a rigorous Write protect notch ~ (some diskettes do ~ not have this notch ) !l Permanent - - label Exposed recording surfaces Diskette in permanent protective jacket Diskette envelope Your floppy discs should always be stored in their jackets. Never attach notes using paper clips - they can become magnetised. Use a stick-on label instead & write with a felt-tipped pen. series of steps to help ensure that at I.e ast all the hardware components are functioning. Each step is reliant on the successful completion of the previous step. If you do experience a problem during the POST, try it again and this time watch what happens. Try to determine how far into the POST the computer goes before it fails . As . a general indication, this is what happens: • You turn on the power. The computer performs a self test only when full operating power is reached. If you get no further than having fans and discs spinning, together with power to the monitor, you could have a problem with the power supply. Provided all is OK, a power good signal is sent to the motherboard. • A timer chip stops generating a reset signal for the processor when it receives the power good signal. • The processor starts to execute the instructions found at memory location FFFF:0000. Its main function is to provide a direction instruction to the BIOS start location. • ROM BIOS starts then checks flags at locations 0000:0472 and 0000:0473. These flags indicate whether you are performing a cold or warm boot since different POST procedures apply. The warm boot skips most of the POST procedures. • Once POST commences, all major components are tested, including the speaker (when the computer beeps). Problems are indicated by messages to the screen and beeps. • BIDS then performs a ROM scan to find various adapter cards. Adapter ROMs can alter existing BIOS routines, thus establishing new ones. • The BIOS now searches for a boot record on track 0, sector 1 of the first disc drive. If there is a disc present in Drive A, the BIOS attempts to continue the start procedure. If the disc is actually a data disc inadvertently left there since the last time you used the computer, you will get the message: Non-system disc or disc error. Replace and strike any key when ready. Replace the disc with a DOS system disc (ie, a disc with COMJUNE 1990 71 COMPUTER PART# SIZE AMIGA AMIGA AMIGA 02930 02932 02938 3.5" 5.25" 3.5" CAPACITY 880K 360/880K 880K AMSTRAD 02904 3.5" 720K ATARI ATARI 02916 02918 3.5" 5.25" 720K 3601720K IBM IBM IBM IBM 02946 02948 02950 02952 3.5" 3.5" 5.25" 5.25" 720K 1.4MB 360K 1.2MB WITH WITH WITH WITH TOSHIBA TOSHIBA ZENITH ZEN ITH 02970 02972 02976 02978 5.25" 5.25" 5.25" 5.25" 360K 1.2MB 349 .00 399 .00 360K 1.2MB SUIT TOSHIBA LAPTOP SUIT TOSHIBA LAPTOP SUIT ZENITH SUPER SPORT SUIT ZENITH SUPER SPORT COMPAQ COMPAQ 02980 02982 5.25" 5.25" 360K 1.2MB SUIT COMPAQ SLT 286 SUIT COMPAQ SLT 286 349.00 349 .00 COMMENTS PRICE WITH ON/OFF SWITCH WITH ON/OFF SWITCH INTERNAL KIT FOR A2000 249.00 299.00 229.00 FOR PC1512/1 640 269.00 WITH POWER SUPPLY SWITCHABLE , WITH POWER SUPPLY 269 .00 299.00 ADAPTER ADAPTER ADAPTER ADAPTER INTERFACE INTERFACE INTERFACE INTERFACE & & & & CABLE CABLE CABLE CABLE 299.00 329 .00 299.00 329.00 349.00 399.00 ALL TOSHIBA/ZENITH/COMPAQ DRIVES INCLUDE EXTERNAL POWER SUPPLIES, INTERFACE AND CABLES WE ALSO HAVE A RANGE OF DRIVES FOR OTHER BRANDS SUCH AS APPLE AND MACINTOSH AS WELL AS A RANGE OF BARE DRIVES IN 360K/720K/1.2MB/1.44MB/2.88MB FORMATS Have you seen our catalog? Write or phone today for your FREE copy. Over 100 products shown with full details and specifications! BEWARE! We are aware of some cheap drives coming from Taiwan, usinB inferior drive mechanisms. REMEMBER: ALL ROCTEC drives use UALITY Japanese mechanisms and are covered by a 12 month warranty. The drives are supported by us under an exclusive agreement with the manufacturer. DEALER ENQUIRIES WELCOME Plii[ [eeson 's PERSONAL COMPUTER MARKETPLACE PHONE (02) 418 6711 FAX (02)4186713 Mail Order Address: P.O. Box 1100 Lane Cove NSW2066 FREIGHT CHARGES Include $10 with order for all normal items· heavy items, e.g. monitors add $15. 14 day money back guarantee Order by phone (use credit card), by fax or by mail. Unless insurance is declined it will be charged at 1% of total purchase. This is for your protection. PRICES VALID AT 1 MAY 1990 Ptyltd Sealed chamber Mounting chassis Read/wrile head Cut-away view of a hard disc drive. Although more reliable than floppy disc drives, they can fail so always make back-ups. MAND.COM on it) or remove it from the drive, then press any key to continue. • The BIOS now looks to the hard disc for a master boot record and if found, the sector is loaded and the program executed. • The boot record now takes control from the BIOS to load xxx10.COM and xxxDOS.COM. At this stage xxxIO.COM is firmly in control. • xxxIO.COM uses xxxDOS.COM to load and pass control to the discbased command processor, COMMAND.COM. e COMMAND.COM loads and runs the AUTOEXEC.BAT file, if present. e AUTOEXEC.BAT processes all the commands contained therein and finally displays the DOS prompt or a menu, as the case may be. Typically, problems are found during the POST checking phase and I when the BIOS requires a boot record. Mostly, the POST problems are memory or device related. Further problems can be experienced with discs left in Drive A and faulty or deleted COMMAND.COM files. Try booting with a DOS disc in Drive A if you can't get to the final stages, and note any messages from the computer. Disc disasters Discs create more obvious problems than most other PC components, so it seems like a good idea to start here. Naturally, we are all smart enough not to fold diskettes in half prior to mailing - but is the post office smart enough to deliver them in the same condition? Make sure you use a disc mailer to send diskettes through the post. If this is not possible (or you're too stingy), pack the disc with reasonably stur- • o- The 3 + -inch micro discs are more robust than their 5-25-inch cousins since they have the advantage of a more rigid case and a sliding metal protector for the read/write area of the disc. dy cardboard and bubble-wrap (if available). Should you have the misfortune to receive a disc that has been folded or creased, try to ease out the wrinkle in the disc cover. This is usually what stops the disc from spinning correctly. Once the cover is fairly straight, you will often find the data accessible. Copy the contents as soon as possible then discard the disc unless you like to live dangerously. Another possibility is to very carefully open the damaged jacket and place the disc in a new jacket. This has worked successfully once only, but desperate people need desperate solutions. Once again, copy the contents and discard the old disc. Discs of all types should avoid a trip through the X-ray machine at the airport - although I do know of several cases where discs in plastic boxes have been through and survived unscathed. The amount of damage likely to occur is inversely proportional to the number of backup copies available. If you have no backup, it is sure to be ruined. Floppy discs should avoid magnets of all kinds - particularly paper clips stored in those cute magnetic holders on the desk. Floppy discs don't know this, of course, so you have to make sure that they are not placed in harm's way. Don't put paper clips on 'em! If you must attach a note to the disc, use Post-it notes or similar. They are easily removed and create few problems. Likewise, keep your discs in their jackets and in a box, not on the floor where the legs or wheels of a chair can maim and destroy data at an astonishing rate. Generally, you should not have any problems, but err on the side of caution and copy the contents ASAP. The 3 + -inch micro discs are more robust than their 5.25-inch cousins since they have the advantage of a more rigid case and a sliding metal protector for the read/write area of the disc. You will have less problems with dirt and dust contamination using these discs, but remember at all times that nothing and no-one (least of all me - Backup, what's that?) is perfect. ~ TUNE 1990 73