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---------------------------------------------------------------- LAPTOP COMPUTERS ---------------------------------------------------------------- This tutorial contains three sections: travelling with laptops, rechargeable battery care and resources for laptop users on CompuServe. For additional information on purchasing a laptop computer, see the section on laptop purchasing contained within the PC-Learn tutorial titled BUYING A COMPUTER. Laptops are made to travel. Their small size and potent features make computing on the road a snap. Consider using this assortment of tips which seasoned laptop owners have come to rely on.... Airports are a frequent transit point for laptop owners. Be sure to be prepared for a SPEEDY passage through airport security by being aware that in most cases you MUST boot up the laptop so that a DOS prompt, menu or other sign of visible activity is displayed on the screen. Security officials do this for a reason: if a laptop computer has been tampered with or hollowed out to serve as an empty shell for explosives or weapons, the machine will not boot up or operate. By forcing the laptop owner to activate the machine, airport security is effectively screening for tampered machines. Once you know this, several important tips are quite useful. Always carry a BOTH a fully charged battery and AC adapter with the laptop. No power means no possibility of booting the machine and your laptop might be forced to remain behind! To speed the process on laptops equipped with hard drives try an experiment. Prepare a bootable floppy disk with DOS system files and a short AUTOEXEC.BAT program which boots the machine rapidly since DOS usually tries to boot from a floppy first and then the hard drive second. Now time how long it takes to boot from the floppy as well as the hard drive. Whichever is faster is the one you want to use to speed your trip through airport security. But ALWAYS take the bootable floppy as well. Why? If your laptop hard drive becomes damaged in transit - a possibility in today's airport environments - then you have a floppy backup which will also get you through airport security. Cursor size and blink rate on many laptops are atrocious. Third party software utilities are available which can alter both size and shape of the cursor - we will discuss these in more detail in the software section of the Laptop tutorial. However the point to be made is that you might find one ideal cursor size and blink rate for airplane use and a DIFFERENT cursor size and blink rate better at the office or in the airport. Try various combinations in various lighting. Several different cursor configurations are quite handy when travelling under varying lighting conditions. By the way in a pinch, The WordPerfect word processing package has just such a utility you might want to dig out if you own WordPerfect but have never used software cursor control utility! Did your portable printer malfunction and crash while you are on the road? Or maybe you just don't want to carry your printer at all. Here's an obvious idea: use your laptop and modem/faxboard to fax your file to the hotel front desk fax machine and pick it up there! If your modem lacks fax transmit capability, send the file via modem to CompuServe and let them re-send it to your hotel fax machine using their fax transmission capability. Worried that the fax image might fade or curl with heat or handling? Then xerox copy it onto standard paper which is a more permanent material than fax paper. Speaking of modems, the smallest and most "laptop useful" modems are available from U.S. Robotics (call 708/982-5010.) Their World Port modem is truly tiny, fully-featured and ruggedly designed for travellers. Hayes has also produced the Pocket Modem (call 404/449-8791.) Some of the most clever portable modems do not even need battery power - they draw current from the computer or telephone line. Hotels and airlines always have carpeting. And carpeting is productive of electrical static. Shuffle across the floor in most travel facilities on a dry or cool day and you get a spark when you touch the doorknob. This same static electricity buildup can ruin the EPROM chip in your laptop keyboard when you sit down to use the laptop. Be sure to first touch a bathroom faucet with a coin. To eliminate static in your hotel room, just take off your shoes and socks! Carry extra charged batteries on long flights or international flights. Seems like a simple tip, but that battery pack you bought two years ago may finally decide it has a one hour life somewhere over the Atlantic Ocean. Rechargeable batteries cannot be recharged forever - after two to five years they begin to die. Be sure you know how to turn off the speaker beep facility in your laptop. Crowded airplanes indicate courtesy. Third party software utilities exist which will provide this capability if you own an older laptop without this software or hardware feature. More about this in our software tutorial. Conserve power on long flights. Turn down the screen brightness to save power. Use the auto-resume feature if your laptop contains the capability. Switch to slow mode or lower the processing speed of your CPU chip. Your instruction book may mention some or all of these features. Some laptops have a variation of the auto resume feature that even allows you to change batteries right in the middle of a program. Check your manual. Might be a lifesaver on a plane trip. Save still more power when travelling by investigating software ram disks or virtual disks which, unlike a spinning hard drive or floppy, use far less power on long airline flights. DOS itself comes with a reasonable although rudimentary ram drive called VDISK which all laptop owners should check out. You can also obtain third party shareware, commercial and public domain ram disk software. Of course be sure to save your work to a floppy or hard disk before you turn the machine off since a ram disk operates purely in memory and MUST have power to maintain your data. If you travel out of the country, be sure to register your foreign made laptop with U.S. Customs when you depart - so that upon return you are not forced to pay duty on a machine you bought in the U.S. but which customs officials will suspect was purchased overseas. This can be a sticky subject. Contact a local customs office for instructions on registering your machine prior to departure. Travellers should also consider etching your name, address, telephone and social security number onto the machine in several places. Although this may decrease the resale value of the laptop, it also increases chances of recovery in case of theft. Don't make the mistake of etching ONLY your social security number onto your laptop. Federal privacy laws prevent release of your social security records even to some law enforcement agencies and in that respect having only your social security number on valuable items is probably next to worthless as a security item. Hotels are getting better about providing modular plug in telephone jacks for laptop users who need to hook up a modem. But it seems the telephone jack on the wall is always ten feet from the nearest table where you laptop sits. Solution? Always bring a modem extension cord with in-line connector. Makes laptop modem work a joy! Another tip: use the hotel's toll free 800 number to call ahead and doublecheck that your room is wired with modular plug-in telephone jacks. Takes a moment and costs you nothing! Speaking of plugs, investigate the new breed of miniature surge supressing AC adapters if you travel to foreign countries whose voltage can be less reliable than that in the U.S. You can obtain special anchor plates or straps which attach to the bottom or side of a laptop with permanent glue. A flexible steel cable and lock lets you secure your laptop to a hotel radiator or piece of furniture and defeats all but the most determined thief. For those who absolutely need telephone links when travelling, consider purchasing an acoustic modem coupler which works with all telephones when you cannot plug your modem into the wall. Acoustic couplers work by attaching directly to the mouthpiece and earpiece of any standard phone and transfer data directly by sound transmission. By the way, in overseas areas you will soon find that you need a maddening array of special adapters to hook your modem to the telephone line directly. An acoustic modem coupler is the only truly "universal" adapter which will connect to all telephones throughout the world. Another modem tip when using hotel telephone lines: arrange with the front desk or operator to ALWAYS put your call DIRECTLY through without intervention. Many hotel system route your call through a switchboard which prevents your modem from getting a dial tone! Diehard laptop users who communicate with the head office via modem should also investigate remote computing software which we will discuss later. Remote computing software allows you in your hotel in New York to call San Francisco by modem and then connect directly with your desktop computer or office LAN network. Once connected, you can run your word processor, obtain files, check figures on the office spreadsheet and more. In essence your laptop functions as a remote keyboard for a computer which is thousands of miles away. Shareware, public domain and commercial software packages of this type are available. But if you do this, here is one important tip many travellers learn the hard way: ALWAYS leave a note for the maintenance person or janitor which tells them not to turn off what appears to be your idle office desktop computer. Oh, and while you are gone, turn off the desktop monitor but leave on the pc if you plan to compute remotely. This saves power and prevents screen burnout! Need to test if two files are slightly different as you check newer document files against older ones? Or maybe just backup all NEWER revisions of your files to a floppy or transmit them by modem to the head office? Use the DOS XCOPY command to track down differences between two files such as word processing documents. DOS also previously had an older File Compare command called FC which accomplishes the same thing. Sidekick version 2 has a reconcile feature and Lap-Link can transfer files between to computers and check dates and times to make sure you are obtaining the newest version of a file or to ensure that both computers indeed have the latest file. By the way, here is an example of how to use the DOS XCOPY command to copy all files from ALL subdirectories on a laptop hard drive named C: onto a backup floppy in the A: drive which have been updated on or later than March 15, 1992. Very handy when you are on the road and want to copy or prepare for modem transmission all of your updated files for the head office. At the DOS prompt type: XCOPY C:\*.* A:/S/D:03/15/92 Consider travel insurance for replacement of your laptop in case of theft. Contact Safeware at 800/848-3469. Business travellers often have to present VERY important presentations with their laptops. Essential job proposals, contracts, crucial price schedules. If it is important to your business, always make a backup copy on floppy disk. Seems simple, but many business users discover that their hard drive equipped laptop has crashed due to airport handling in transit. A floppy can save the day and in a pinch you can rent a computer or borrow one from your client. If data matters, put it on a floppy. Make sure you ALWAYS carry a null modem cable and file transfer software with your laptop when travelling. You can probably patch into another desktop computer to transfer files in emergency, but without the null modem cable and software you are stuck. Practice transferring files between several computers before you travel so you have the process comfortably memorized. For the truly worried traveller, also carry a pair of gender changer plugs which allow hookup of male to male and female to female cable connections. Also a 25 to 9 pin plug adapter. Laptop computer die in transit? Carry a set of jewelers screwdrivers and floppy disk cleaning kit. If a few simple things such as this won't fix it, then grab the yellow pages and look under computer rentals. By the way, many hotels maintain rental laptops for business travellers. But the secret is that the rate is far cheaper by renting from a local vendor than the hotel. Make a few phone calls and get a laptop delivered to your hotel suite in case of emergency. The smartest travellers call ahead to their destination and reserve a backup laptop in case of problems at a local vendor. If the laptop is not checked out a small retainer fee is kept by the vendor. This can be done by a charge card and a long distance phone call. Same goes for renting LCD projection panels for business meetings. Consider obtaining a CompuServe account for modem use if you travel frequently. You can obtain online support for laptop computer problems directly from the manufacturer, download special software utility files, transmit important files to the home office, send faxes when all you have is a modem which lacks fax transmit capabilities (CompuServe converts your modem transmission and sends it on via their fax equipment.) Lots of good ideas and special laptop discussion forums for business travelers. You can even book hotel and airline reservations directly by modem using CompuServe, too. Laptops, travel and CompuServe go together handsomely. Did your ribbon die in your portable printer? Just not black enough? Stick some fax paper in the printer. It is heat sensitive and will frequently pick up an image without a printer ribbon. Amazing but true. This works with dot matrix printers. Do not try it with laser printers. Check ahead for special regulations. Example: in Germany modems are regulated under certain security laws - presumably spies could use them to transmit data. You must have a "modem permit" in that country or your equipment can be confiscated. In other countries and some developing nations such as Africa and India confiscation of computer equipment is common - even if all of your registration and travel documents are in order! In those cases you might be better off leaving your computer at home and bringing a tape recorder or notepad. Just because you own a computer does not mean you can use it in an unrestricted fashion while you travel! Tempted to use one of those inexpensive overseas power convertors to adapt your AC plug in convertor to European current? DON'T DO IT without first checking with the manufacturer. Those inexpensive current convertors work fine when changing high voltage overseas current to lower voltage US current for things like shavers because they reduce the voltage. The problem is that most of the world uses 50 cycle AC current versus the normal 60 cycle AC current in the U.S. Computers CANNOT run from these inexpensive convertors and damage may occur. Find out what device the manufacturer supplies or recommends for travel outside of your country of residence. ---------------------------------------------------------------- RECHARGEABLE BATTERIES AND LAPTOP COMPUTERS ---------------------------------------------------------------- No other topic seems to inspire more opinion and comment than the proper care and handling of rechargeable laptop and notebook computer batteries. Should you slow or fast charge them? What is the true life of a rechargeable battery after which it must be disposed? Do rechargeable batteries have a "memory" effect? Can nickel-cadmium batteries explode when charging or discharging? Although this tutorial may seem technical in places, try to read ALL of it since battery power may be your only source of laptop power on many occasions. For many portable computers a variety of rechargeable battery options exist today. But frequently it comes down to the old standby: nickel-cadmium batteries. Ubiquitous in consumer electronic items such as shavers, flashlights, toothbrushes and radios, nickel-cadmiums or "nicads" are a reasonable balance of power, cost and weight and are used by many computer manufacturers as the portable power source of choice. Let's scratch the surface on the topic since there is QUITE A BIT the manufacturer doesn't tell you about nicads.... Glance at the following chemical equation which is at the heart of the nickel-cadmium cell reaction. Don't get overly anxious because high school chemistry was not your favorite subject. We'll take things slowly.... <----- Cd + 2 NiOOH + 2 KOH -----> Cd(OH) + 2NiO + 2 KOH 2 In this highly simplified reaction sequence, electricity is generated when the reaction proceeds in the direction of the right pointing arrow, the discharge cycle. If the reaction proceeds in the left direction the cell is charging. In simplest terms, a nicad cell (a battery is constructed of several cells hooked together) has a positively charged plate of nickelic hydroxide and a negative plate of metallic cadmium. The liquid between the positive and negatives plates which facilitates this chemical reaction is usually a dilute solution of potassium hydroxide - similar to lye or the Draino (tm) solution your pour down the sink to clean your plumbing. When discharging and thus producing electricity, the nickelic hydroxide is reduced to nickelous hydroxide as hydroxyl ions from the potassium hydroxide electrolyte combine with the cadmium metal of the negative plate of the cell to form cadmium hydroxide. Cadmium is oxidized when this happens and electrons are provided into the external circuit, such as your laptop computer. When charging, the process reverses and hydroxyl ions combine with the nickel which accepts electrons from the external charging circuit. Notice that the electrolyte, potassium hydroxide is unchanged with two atoms or units produced on both sides of the chemical equation whether charging or discharging. This is why you do not need to add more water to a nicad battery which operates as a sealed reaction container. It regenerates its electrolyte in both the charge and discharge cycles. All of this is an ideal nicad cell. The real world of computers and rechargeable batteries is not quite that simple. The first SERIOUS item to consider is that all nicad cells and batteries generate gas during both the charging, and to a lesser extent, discharging cycle. During recharging, oxygen gas is generated at the positive electrode while hydrogen gas is produced at the negative electrode. In other types of rechargeable cells, a standard lead acid car battery for example, these gasses are usually released into the atmosphere. The nicad cell does not have this luxury since it must operate cleanly and with minimum release of gasses or liquids. To minimize hydrogen gas release, nicad cells usually have an oversized negative electrode which tends to reabsorb hydrogen gas. In addition oxygen is recycled by combining with metallic cadmium to produce cadmium oxide. So called "fast-charging" nicad cells prevent gas buildup and dissipate some of the heat generated during the quick charge cycle by further enlarging the electrodes. Heat and gas buildup is thus controlled and kept to tolerable limits in quick charge nicads. The first of several lessons which can be derived from this technical discussion is that the buildup of hydrogen and oxygen gas during the charging cycle is normally dissipated unless HIGH recharging rates are attempted or unusually high temperatures are produced. If the nicad cell is charged at abnormally high rates the oxygen gas cannot dissipate and will EXPLOSIVELY rupture the cell. A safety system of sorts exists within the design structure of most nicad cells via a pressure venting system - a plastic diaphragm membrane at the top of the cell and small external hole or "exhaust vent." In theory the system safely vents excess pressure and then reseals. In practice the resealing is never complete and the cell may continue to ooze caustic electrolyte or worse the vent may not open soon enough and the cell may simply explode. The vent is really designed for SEVERE charging or discharging rates. In normal use it should NEVER activate; if it does, the battery should be discarded. In cases of massive overcharge or discharge the safety vent is usually too little too late and a dangerous battery explosion takes place anyway. During rapid discharge - short circuiting the nicad cell or battery with a piece of wire, for example - gas buildup and heat can be generated and a violent explosion can occur. Another reason why nicads can explosively burst when short circuited and forced to discharge quickly is that they have relatively low "internal resistance" which allows them to dump their electrical capacity quickly and with explosive force. Common zinc carbon batteries have a much higher internal resistance and when shorted may produce serious burns to your fingers from melting wire but usually will not explode due to sudden gas buildup. On the point of sudden nicad discharge by short circuit you might be tempted to say that it would be highly unlikely with a portable computer battery. Not so. Tales are told of laptop computer batteries which have exploded when a careless owner shoved several fully charged nicad batteries in a travel case with a set of spare keys. If the keys accidentally contact both the positive and negative poles of the nicad simultaneously, a violent explosion reaction can occur! Clearly nicads have some unusual features to be respected and understood. Be careful with charged nicads and treat them as the small "hand grenades" which they can become. Heat, sudden short circuits and high rates of charging are the problem in this area. The correct operating temperature for discharging and recharging nicads is from 65F to 85F, according to most manufacturers. High and low ranges of from +32F to 115F are possible as upper and lower limits if nicads MUST be used in extreme environments although discharge and recharge efficiency may be adversely affected - it may require more power to fully charge the battery, charge may not be held for as long on the shelf after charging and finally discharge may not produce a full three or four hour computing session at these severe temperature ranges. Electrically, individual nicad cells - the units which are hooked together to produce the final battery - have a charged voltage of 1.25 volts. Nominally this drops to 1.2 volts under actual discharge use or "load" in the electrical device. Individual cells are strung together in "series" with the positive terminal of one cell touching the negative terminal of the next cell in sequence to raise the voltage to that suitable for the electrical device. Thus two cells hooked in "series" as a battery produce 2 X 1.2 volts = 2.4 volts. Likewise, three cells connected as a battery produce 3.6 volts. By the way, ordinary flashlight batteries of the carbon zinc type have a nominal voltage of 1.5 volts compared to the 1.2 volts of the nicad cell. Nicad batteries have an unusual and highly characteristic discharge behavior which is best described as "a stable discharge plateau then sudden voltage drop." Essentially a fully charged nicad battery provides constant voltage and current until near its exhaustion at which point the voltage SUDDENLY DROPS and the cell is, for practical purposes, completely discharged. Compare this to standard carbon zinc and alkaline batteries which gradually drop in voltage and amperage through the discharge cycle of the battery. In use nicads tend to be stable, then die suddenly at the end while conventional non-rechargeable batteries slowly decay in voltage as their power is consumed. One conclusion you might draw from this is that when your portable computer beeps that the nicad battery voltage is nearing exhaustion you literally have only moments of use left! The good news is that nicads produce dependable power through their discharge cycle which is highly desirable with digital data and computer memory devices. The "memory effect" of nicads is perhaps the most discussed and misunderstood phenomenon associated with nicad cells and batteries. An undesirable and somewhat unique characteristic of nicad batteries that they can develop a "memory" which can decrease either the capacity or voltage of the battery. The first type of memory problem in nicads - voltage memory - is caused by sustained charging over many days or months. This memory effect can be accelerated by high ambient temperature extreme duration of charge and high rate of charge. In effect the battery is charged for such a long period of time or at such a high rate or high temperature that the efficiency of the chemical reaction is impaired and proper terminal voltage readings are not achieved. In the second, more common "memory capacity" problem, the nicad loses the capability to deliver its full power capacity. One cause of this peculiar memory problem is the FREQUENT PARTIAL DISCHARGE of the battery - use for perhaps 30 minutes - and then full recharge again. In effect the nicad battery "learns" that only part of its capacity is used and over several cycles of "partial depletion and then full recharge" that less then full capacity is needed. It will then be unable to deliver a full two or three hour standard discharge in normal use. Fortunately memory effects are usually temporary and can be reversed. The chemical basis for these two memory effects is not fully understood, but may have to do with obscure oxidation reactions which temporarily coat the internal electrodes of the battery with thin layers of complex non-reactive chemical compounds which can be removed by more fully "exercising" a nicad through a complete charge/discharge cycle. It is claimed by many manufacturers that this odd memory effect of nicads has been largely eliminated due to modern manufacturing methods. However to some degree this may in fact be a result of newer charging systems and the relatively complete discharge of nicad power by modern laptops. In effect the batteries are charged and discharged in a more appropriate manner by most laptop users so memory effects "appear" to be no longer a problem. Both memory problems - voltage memory and capacity memory - are usually temporary and can be corrected by discharging the battery to or very near its exhaustion point (optimum drawdown voltage is about 1.0 to .9 volts for a standard 1.2 volt nicad) and then recharging it to full capacity. Repeat this discharge- recharge cycle from 2 to five times and frequently the nicad will lose its memory for the "partial capacity" and again provide a full 3 or 4 hours of use in most laptops. Actually, frequent FULL discharge and recharge prolongs the life of a nicad. The more you use them the longer they last! Most folks who want to completely discharge laptop nicads simply leave the computer on until it runs down. A much faster method is to use the following batch file which continuously reads the directory of a disk and writes the contents to a disk file. The continuous disk access drains nicad power much faster. If you are not familiar with batch files, read the batch file tutorial elsewhere in this program. Here's the three line batch file. To stop the batch file at any time press the control and break keys simultaneously. When finished you may wish to erase both the batch file and the small file named "test" which it creates. :start dir>test goto start As an aside, the newer nickel-hydride batteries used in some laptop and notebook computers do not seem to suffer from memory effects. But these batteries are more expensive and not in common use by most laptop manufacturers. Nicads do eventually fail. And for various reasons. Temporary or partial failure due to memory effects was discussed in the previous paragraphs. Permanent failure - usually between 3 to 5 years into the life of a typical nicad can happen due to the growth of characteristic "whiskers" of conducting chemical compounds which effectively bridge the internal gap between the positive and negative electrodes inside the battery. Effectively these small contamination deposits gradually short circuit the battery internally which leads to inability to charge or discharge. Some clever electronic hobbyists build high current "surge" power supplies which can burn open these internal deposits and reopen the gap between positive and negative electrodes. A risky practice at best - given the explosive reputation of nicads - but "zapping" nicads in this manner has been documented as one way to add life to an otherwise dying battery. A risky an usually ill-advised attempt to salvage an otherwise dying battery. A different permanent failure can result from premature loss of the liquid electrolyte from the battery. High temperature and/or high charging rates are usually the cause here. Quick-charge batteries frequently fail due to this problem if their charging circuits are not properly designed. If the top edge of the cell which contains the fail safe pressure release valve has a buildup of white corrosion powder this is probably the residue ot the expelled electrolyte and the cell may be on its way to failure and should be replaced. Note that you can only see this corrosion buildup on the top of the SINGLE nicad cells which are usually encased within a surrounding plastic battery housing. The plastic housing may show little problem externally. Generally, however, the average computer user should not attempt to open the protective plastic case of the battery to examine each cell. If the manufacturer seals several individual nicad cells in a plastic battery container it is for GOOD reason and your own personal safety. As a rule quick charge nicads do not last as long a regular nicads due to heat build up during the charging cycle. So how long will a nicad battery last before complete failure occurs? Manufacturers estimate LOW figures between 500 and 1,000 full charge and discharge cycles or about 3 to 5 five years, as noted above. Some nicads have been known to approach 5,000 to 10,000 charge and discharge cycles before permanent failure. Excessive quick charging, heat buildup, infrequent use and lack of full charge all contribute to shortened nicad lifespan. Charging and discharging mathematics... Charging nicads is generally done automatically by a charging circuit. Two practical pieces of advice: 1) if the battery becomes VERY hot something could be wrong 2) if the manufacturer tells you that the battery will be fully charged after a certain length of time although it can be left charging longer you will probably do the nicad a favor by removing it after full charge is reached. Some clever nicad users simply attach an inexpensive electrical timer - similar to those used to turn lights on and off in the evening - directly to the nicad charger to prevent overcharging. Generally nicads have a proper charging rate which depends on each manufacturers recommendation. For standard nicads which are NOT quick charge types the proper slow or "trickle" charge rate is determined by dividing the ampere hour capacity of the battery by 10. For example if a nicad has a total capacity of 1 ampere hour, dividing this by ten (1/10) produces a correct trickle charging rate of .1 amps or 100 milliamps. Quick-charge nicads can accept a charge rapidly and the suggested charging rate is determined by dividing the ampere hour capacity of the battery by 3 rather than by 10. These figures represent the trickle charge rate which theoretically means the nicad "could" be safely left charging indefinitely without harm. Higher efficiency chargers are designed not to simply trickle charge nicads but start a discharged battery at a HIGH rate of charge and then taper the charging current back quickly to the safer "trickle" charge rate once full charge is reached. Usually for regular nicads this "initial surge charge" can be as high as the ampere hour capacity divided by 3. For quick charge nicads this "initial surge charge" can be as high as the ampere hour capacity divided by 1. Obviously these are very high charge rates and are provided to discharged batteries and then quickly discontinued once full charge is approached. Clearly a charging circuit of this sophistication is expensive and may even contain its own microprocessor to sense the discharge level of the nicad and calculate the optimum charge rate, time and trickle charge transition. Since we have previously discussed the adverse affect of heat on nicads it is essential to note that NICADS SHOULD BE CHARGED IN A COOL OR ROOM TEMPERATURE location since they normally generate heat when charged. If you minimize heat buildup - especially during the charging cycle - you will prolong the useful life of your nicad battery. Discharging a nicad - especially if you are trying to remove a "memory" problem such as that discussed earlier does NOT mean discharging a cell to zero volts. Usually the correct discharge voltage is about 1.0 volts. This may seem odd when you consider that the fully charged cell has a 1.2 volt reading, but in fact at 1.0 volts a typical nicad cell has released about 90% to 95% of its energy - another eccentric, but predictable behavior of nicads given the rapid "voltage drop off" as they near the end of their three or four hour life in a laptop computer. Shelf life. While carbon zinc and alkaline batteries can hold their charge for years, nicads lose their charge relatively quickly. Although it varies, one quick rule of thumb is that a typical fully charged nicad will lose roughly 25% to 35% of full charge in one month. Then another 25% to 35% of THE CHARGE REMAINING in the next month. And so on and so on. Thus if you have several nicad batteries you want to charge for a trip you will be taking in a month, it is probably better to charge ALL OF THEM the final week just before the trip rather than the month before. For want of a better phrase, this might be called "shelf discharge" and is normal with all nicads and has to do with slight electrical leakage and chemical compound decay internally within a charged nicad which sits on a shelf. Cooling or refrigerating the nicad (but NOT freezing) will slow this "shelf discharge" since you are cooling and slowing the breakdown reaction. In fact ALL batteries will last longer when refrigerated until they are used. Simply store them in individual sealed plastic bags (to minimize moisture condensation) and place them in the refrigerator. And so we conclude with a little summary.... 1) Do exactly what the manufacturer suggests for both discharging and recharging a nicad. 2) Keep temperatures - especially during charging - cool or at normal room temperature. 3) Never short circuit a nicad intentionally or accidentally. 4) Try cycling a nicad through several COMPLETE discharge and recharge cycles if it "appears" to be faulty an incapable of operating your equipment for a normal three or four hour operating period. 5) Remove nicads from charging circuits or discontinue charging when full charge has been reached. 6) Watch for white flaky corrosion deposits on the upper edge of the cell near the pressure vent this can mean impending cell failure and electrolyte loss. 7) Dispose of permanently defective nicads properly - contact the manufacturer for instructions since cadmium is a dangerous toxic metal and has been banned from many dump sites. Try calling your local city hall and ask who can answer a question about cadmium metal waste disposal. 8) When the nicad battery power begins to drop near the end of a discharge cycle it will drop VERY QUICKLY due to the rapid characteristic dropoff of nicads. Prepare for laptop shutdown quickly. 9) Cycle your nicads through a FULL DEEP discharge and FULL COMPLETE recharge frequently - they will last LONGER before you must dispose of them and deliver MORE power when used. 10) Infrequently used nicads should be charged and discharged at least once or twice every two or three months to prolong their usable lifetime before permanent failure. 11) If your nicads are stated by the manufacturer to be quick charge type, you can probably prolong their life by slow or trickle charging them (if your charger provides that option) since you will minimize heat and gas buildup within the cell. Just because they can be quick charged does not mean they MUST be quick charged. Nicads last longer and deliver more power when not driven to extremes of temperature or overcharging. ---------------------------------------------------------------- LAPTOP RESOURCES VIA COMPUSERVE ---------------------------------------------------------------- After a while you begin to wonder. Is there a single centralized source for laptop and notebook computer information? Somewhere you can ask questions, comparison shop among various portable computer models, locate specialized laptop software and obtain tips on travelling with portable computers? No problem. Try CompuServe - a vast computer network accessible by computer, telephone line and a modem. Before we highlight some selected resources for portable computer users a little background concerning the CompuServe service.... CompuServe. Telephone: 800/848-8199 or 800/8488990. 5000 Arlington Centre Blvd, Columbus, OH 43220. Claiming that more than 800,000 members can use the service at any one time, Compuserve is without doubt the most extensive online service in existence. The vastness can be overwhelming with literally hundreds of conferences including gardening, coin and stamp collecting, legal research, music, games, foreign language training, desktop publishing, travel planning, banking, ecology, portable computers and more. Over 1,400 databases are contained online and users can send and receive messages and software from anywhere in the world. Compuserve users can use an attractive basic monthly service plan, costing $7.95 per month, which includes messaging, limited but useful services such as Consumer Reports, News, Weather, Encyclopedia, Peterson's College search and others. Additional forums and advanced services are charged on a per minute connect time basis with additional surcharges for advanced services. Connect time rates for forum access and advanced services cost about $6.30/hour at 300 baud, $12.80/hour at 1200 or 2400 baud and $22.80/hour at 9600 baud. Depending on services accessed, Online databases, such as the IQuest service of Compuserve provide access to corporate financial data, full text magazine articles, legal data, medical topics and more - although a surcharge of between $2 to $100 per search on advanced database searches can make Compuserve expensive but cost effective if vital data is needed quickly. An online member directory and national telephone and address database is also available. A Compuserve starter kit is available from most retail software stores ($39.95) or can be ordered from Compuserve via their toll free telephone number. The starter kit includes a $25 credit for online time which more than pays for the included software and reference materials. Compuserve also publishes a richly detailed monthly magazine for members which includes articles on travel, research, shareware, forums of interest, shortcuts and news for members which is well worth the price of basic subscription services described above. Compuserve is owned by H&R Block Company. What is available on CompuServe for laptop and portable computer owners? There is so much information it almost becomes a necessity to organize the topic into three areas: forums, files and services. Let's start with forums. Containing both message areas and specialized library areas where software files are located, forums are the primary conduits of specialized information. All can be quickly accessed using a GO command. For example GO PALMTOP would quickly transport you to the palmtop computer forum which contains information on devices such as the Sharp Wizard, Casio BOSS, Psion and Poquet computers. Here is a brief list of applicable CompuServe forums and their specialty areas which laptop and portable computer owners should investigate. The IBMHW forum, library 6, is an especially rich treasure trove. Laptop, portable and notebook computer interest areas Forum name Focus/specialization IMBHW IBM hardware forum, see library 6, small computers PALMTOP Palmtop computers and personal organizers TRAVSIG Travel special interest group CEFORUM Consumer electronics and the mobile office IBMNET Vendor forums for IBM related hardware/software CLUB Computer club forums, small computers IBMCOMM IBM communications forum EUROPHONES Telephone access numbers (CompuServe) in Europe IBMEURO IBM European users, travelling with laptops info IBMFF IBM file finder, locate files you need Specialized vendor and manufacturer forums... APORTFOLIO Atari Portfolio forum TOSHIBA All toshiba portable and laptop computers ZENITH Zenith laptop and desktop computers EPSON Epson printers and portable computers HP Hewlitt Packard computers, printers HAYFORUM Hayes modem forum M100SIG Tandy model 100 notebook computer CANON Canon portable computers and printers PPIFORUM Practical Peripherals - miniature modems PCVENA Vendor A forum, section 10, Northgate computer PCVEND Vendors such as Dell computer MALL Electronic shopping mall - merchants/vendors Routine commands/helpful GO words and commands BILLING Review your current charges COMMAND List of commands for efficient use RATES Fees and charges for various services FEEDBACK Ask questions on ANY CompuServe topic INDEX Locate a forum, service or topic DIRECTORY Locate a person and his/her ID number MAIL Check your mail, send messages, FAX, postal QUICK Master list of GO words LOGON Telephone access info and numbers TOUR An informative guided tour of the service QALOGON Commonly asked logon/logoff questions NEW What's new this week on CompuServe BYE Command to logoff, exit the service The treasure trove of CompuServe software files of interest to portable computer owners in almost overwhelming; one service which helps you navigate through files bears mention: the IBM File Finder (GO IBMFF). Using this speedy "search engine" you can quickly locate selected software files by keyword, filename, uploading author and other criteria. CompuServe software files are associated with "keywords" which help index them. For example a file on using laptops might contain keywords such as "beginner, laptop, notebook, travel, portable". Using the IBM File Finder you can ask for a listing of all files containing the single word "laptop" or, for a more precise search, BOTH the words "beginner" and "laptop". The File Finder report will tell you the forum (e.g., IBMHW,) library (e.g., Library 6, small computers) in which the selected file resides as well as the filename. Now that you know the details, simply jump to that forum (e.g., GO IBMHW), switch to the library (e.g., DL command, then select library 6). Finally, read a full description using the BROWSE command (e.g., BRO filename). Quick and painless. What types of files are available to laptop and portable computer owners? A sampling.... AIRPRT.ARC (GO IBMHW, library 6) discusses airline travel concerns and issues of laptop computing such as use of laptops while airborne, airport security and X ray inspections. PORTCS.TXT (GO IBMHW, library 6) discusses business situations, mostly oil drilling and prospecting, where laptop computers processed crucial business information and assisted in investment decisions. TRAVEL.INF (GO IBMHW, library 6) contains a clever assortment of tips and accessories for the well-equipped laptop traveler. BC3.COM (GO TOSHIBA, library 5) cursor utility which changes shape from thin underscore line to large block shape for better visibility. 3PARTY.ZIP (GO TOSHIBA, library 4) retailers who can supply specialized memory, modems, cables and accessories for Toshiba laptop computers. LAPKEY.ZIP (GO ZENITH, library 5) a clever utility which lets you redefine the cursor control keys (right/left/up/down arrows) on your laptop. PKL105.EXE (GO ZENITH, library 5) PKLITE allows laptop users with limited disk drive space to compress COM and EXE files to save space - yet files still uncompress and run programs quickly. LAPTOP.ARC (GO TOSHIBA, library 4) discussion of common laptop questions and issues concerning mobile and cellular computing. CLAP.ARC (GO IBMHW, library 6) cursor pulsing speed can be altered for better visibility. TOSHUT.ZIP (GO TOSHIBA, library 2) an assortment of utilities for Toshiba laptops, many of which also work on other portable computer models, which toggle displays, cursor size, report system setup information and more. GAS50.ZIP (GO TOSHIBA, library 2) clever "gas gauge" utility to report nicad battery level for older laptops lacking this feature. BF171A.ZIP and BF171B.ZIP (GO ZENITH, library 4) Back and Forth allows you to rapidly switch between several applications for increased laptop productivity. Switch quickly from word processor to notepad when the phone rings. Jump from spreadsheet to database or other program when you need real productivity. VIDTOG.EXE (GO IBMHW, library 6) switch between internal LCD display and external monitor on Compaq SLT computers. Beyond files, other services await you on CompuServe. If computer research and cost comparisons are what you need, try the following services. Most of these services have surcharges and special connect time charges in addition to normal rates, so check rates before you begin an extensive search.... The Computer Directory (GO COMPDIR) contains almost 10,000 manufacturers and 60,000 product listings. You can search by any word or phrase such as product name or manufacturer name. Likewise, the Computer Database Plus (GO COMPDB) contains reviews of products from almost 150 computer magazines and periodicals. You can search articles individually or in linked groups. InfoWorld Online (GO INFOWORLD) provides further research by way of product reviews on selected hardware, manufacturers and software. Finally Consumer Reports provides general information and ratings for many consumer items such as computers, cars, toys and food (GO CONSUMER). Tutorial finished. Have you registered PC-Learn to receive your bonus disks? Registration is encouraged. Shareware works on the honor system! Send $25 to Seattle Scientific Photography, Department PCL6, PO Box 1506, Mercer Island, WA 98040. Latest version of PC-Learn and two bonus disks shipped promptly!