TECHNOLOGY UPDATE Computer technology update COMPUTER n. Automatic electronic apparatus for making calculations or controlling operations that are expressible in numerical or logical terms; hence -1ZE V.t. equip with, perform by, produce by, computer. Why digital? Imagine, for a moment, that you need to send a message to me; you need to tell me whether to come and rescue you, stay where I am, or send for reinforcements. Your life, and those of others, depend on correct transmission of this message which must be sent using a flashlight and one of two codes. The first code associ- ates each option with a particular number of flashes of the torch - one for rescue, two for stay and three for reinforcements. The second code de- pends on the use of a slider at the side of the torch to vary the strength of the beam; the three possible messages are respectively represented by a weak signal, a medium-strength one, and a bright one. Which coding system would you choose? I'd go for the number-of-flashes option; there's lit- tle chance of misinterpretation (pro- vided both you and I understand the code and can count). The other, intensity-of-beam, method leaves plenty of room for confusion: your "bright" may be my "medium" and our R Whitehorn MaCha, FFRad(D) Consultant radio/agist in private practice, Durban 25 SA JOURNAL OF RADIOLOGY. January 2000 attempts to communicate may end up like those of Allan Donald and Lance Klusener. A coding system that, when broken down into its most basic sub-units, depends on a signal that is either on or off and pays no attention to the strength of the signal, is a digital one. It is their digital nature that has made modern computers so reliable and successful.Why then, you may well ask, does your computer "freeze" so often? Remember, the reliability of the number-of-flashes method of commu- nicating by torch is negated if the sender and receiver are badly trained and don't understand the code prop- erly or can't count. Similarly, badly written software can "crash" even a re- liable digital computer. What's what Let's take a look at the basic com- ponents of a computer. The most im- portant part of the computer is the least impressive-looking: the "box", usually an unchallenging beige colour (but this is changing as computers become fash- ion accessories). It has many wires ap- plied to its back, one or more slits and one or more lights on its front, and makes whirring or clicking noises at times. Within this box live several com- ponents which, being important, will now be introduced. The CPU (Central Process- ing Unit) The brain of the computer. Takes an incoming stream of O's and 1's (data) and, according to instructions (also encoded as a series of 0' sand ] 's) given to it by a program, manipulates this data and sends out a stream of ... yes: O's and] 'so For example if two "pieces" of data, 001 (the number one) and 010 (two), were to arrive at some fictitious processor with the i.nstruction to page 26 TECHNOLOGY UPDATE from page 25 to add them, the processor would spit out 011 (three). If the data arriving at the processor were a very, very long string of O's and ] 's representing a digitised picture of your child, and a series of instructions went to the proc- essor telling it to increase the contrast in that picture, the ultimate result would be another very, very long string of O's and l's representing a more contrasty picture of your child. Memory (RAM - Random Access Memory - and Hard Drive) Picture a craftsman in his workshop. Around his waist is a leather pouch in which he holds those tools that he is currently using. Those tools that he is not actively using are stored on shelves that line one of the walls of his work- shop. The leather pouch is similar to the RAM of a computer, the short-term memory that holds those parts of pro- grams and scraps of data that are cur- rently needed by the processor. This memory communicates with the pro- cessor very quickly, but has far less ca- pacity than the hard drive and is "vola- tile" - when power supply to the com- puter is lost, all data in RAM is lost. The hard drive is similar to the shelving in our craftsman's workshop. It has a large capacity (perhaps a hundred times that of RAM) but fetching data from the hard drive takes much longer than fetch- ing it from RAM, just as getting a screw- driver from the shelf takes longer than simply pulling it out of the pouch. Data stored on a hard drive remains there when the computer is switched off Motherboard If,feeling bored or adventurous, you decide to open your computer and take a peep inside you will see, among other things, a number of cards or boards. The exact number will depend on what you have added to your system, but one that will definitely be there is the "motherboard". This holds the "guts" of the computer - including the CPU and RAM - and may also hold the video (things that appear on your monitor) and sound controllers, which are then said to be "on-board". Video card In the bad old days of DOS your computer's screen may, at a particular time, have been completely blank apart from some witty and enticing statement such as: C> Taken by the eloquence of this you might have been tempted to type: dir. This would have resulted in a whole lot of print appearing on your screen - and that's about as complex as things got, video-wise, in those days. On- screen graphics were confined to thrill- ing stuff like arranging x's, o's and (for the bold) -'s into patterns to depict Mickey Mouse. Nowadays the screen is decorated, even in its "resting" state with thousands (or millions) of colours, lit- tered with icons which await the click of your mouse to launch programs that allow you to show your holiday photos or videos, or (I suppose it must be said, this being a Radiology journal) the chest x-ray of a patient who is a hundred kilo- metres from your rooms. All this in- volves a huge amount of processing, a task which is shunted away from the main processor to a separate video mod- ule, with its own RAM, and often to be found on a separate card plugged into the motherboard. Sound card The sound producing capabilities of home computers have increased from cryptic beeping to the ability to play the overture from Tannhauser (why do we get such a kick out of listening to music over the tinny little speakers that come with our computers? Beats me, but I do 26 SA JOURNAL OF RADIOLOGY. January 2000 it too). As with video, this intense task is often handled by a separate card. Modem If you want to be able to say "yes" when asked "Do you have the internet?" you need a modem, your portal to all the information, sleaze and viruses out there. The modem converts data (in- cluding pictures and sound) between the digital type that a computer under- stands and the analogue type that the phone lines demand. Keyboard, monitor, mouse The purpose of these is self-evident and, for the moment, we'll ignore them. What shall I buy? I will not try to give specific advice regarding the features to be desired in a computer. Such an attempt would be futile, firstly because needs differ from person to person and secondly because the pace of progress would guarantee the obsolescence of the recommendations by the time of their publication, But, some may find a few general pointers helpful. Processor Names like "Pentium" and "PIlI"each denote a class of processors whose mem- bers have similar characteristics and ca- pabilities but operate at different" clock speeds". The clock speed of the proces- sor is indicated by a number like 400 MHz. The performance advantage of a processor which is faster but is within the same class as another (e.g. a PIlI 500 MHz versus a PIlI 450 MHz) is fairly predictable and is roughly pro- portional to the size of the number. The performance advantage of a more re- cent class of processor (e.g. a PIlI versus a PIl) is less easy to predict and is more dependent on what you do with your computer - but it is usually consider- able. My general advice when buying topage27 TECHNOLOGY UPDATE from page 26 a new desktop computer would be to buy into the latest class of processor but to look for the "sweet spot" (the point at which diminishing returns for your money start to set in) with re- gard to processor speed. It is really not going to make much difference, ex- cept for the most demanding of ap- plications, whether your processor is a 550 MHz or a 500, and there's usu- ally a considerable premium to be paid for being at the cutting-edge. RAM Let's refer back to our analogy above, which equates RAM with a leather tool-pouch and hard drives with shelving. Imagine a very slick craftsman - he's a very fast worker but has only a small pouch to hold tools. He has to stop what he's doing repeat- edly to fetch things from the shelves. He'll probably take longer to get a job done than would a slower worker with a larger tool-pouch. Similarly, it's no good having the fastest processor available but being short on RAM. In my opinion, if it's worth having a modern processor, like a PIlI (or its non-Inrel equivalents), then it's worth having at least 64 MB of RAM. Hard drive It used to be as inevitable as death and taxes that you would run out of disk space within a year or two of buy- ing a computer. This remains largely true if you are using your computer COMPANY NEWS MEDISWITCH MediSwitch announces agreement in radiology arena MEDISWITCH, a division of the USKO group, has signed an agreement with Radpac, a developer and pro- vider of medical practice software for radiologists. The deal will see the full integration of MediSwitch's API switch technology with the Radpac system, which treats every patient as a separate account because of the in- .herently unique character of radiology visits. "Currently," explains Peter Kennedy, MediSwitch's business de- velopment director, "All existing us- ers are being upgraded to the new MediSwitch-enabled version of the system at no extra cost." According to Dave Langley, man- aging director of Radpac, the deal is particularly beneficial to Radpac cli- ents because of the cost saving impli- cations. "With a Mediêwitch-enabled version of the software, medical aids will be able to pay Radpac users more promptly, because all invoices will be submitted in real-time, and checked for eligibility and availability of funds. In addition, the medical funds them- selves will only receive notification of accounts once, thus decreasing du- plication, and these will be delivered in electronic format which is easily and immediately incorporated into their databases." The first phase of the deal was ex- pected to be completed by the end of last year. Thereafter, any new us- ers will automatically use the MediSwitch-enabled vcrsion of 27 SA JOURNAL OF RADIOLOGY· January 2000 to do all the things that a modern com- puter can do, for example to manipu- late and store pictures from a scanner or digital camera. If all you're doing is a little word processing and u ing th occasional spreadsheet you'll have a tough time trying to fill one of the modern multi-gigabyte-siz hard drives. But if this is all you're doing, you don't really need a modern "pow- erhouse" computer. Where then, you may ask, can you buy a little, cheap computer with specifications and soft- ware honed down to your limited needs? You can't. The industry says you have to do more with your com- puter. Get cracking. Radpac. The move into niche ar as of the market follows MediSwitch's re- cent deals across the spectrum of th health care industry, including medi- cal aids, fund administrators and Prac- tice Management Software (PMS) providers. About Radpac Radpac is a Windows-based set of comprehensive software modules man- aging administration requirements within radiology practices. The mod- ules are broken up for different aspects within a practice, and are made up of 15 processes, including client records and reports, a pricing structure (with reports) and security built around a bug-free set of development tools. For more information, contact Peter Kennedy at USKO MediSwitch, tel (011) 807·7714, or take a look at MediSwitch's web site on http:// www.mediswitch.co.za http://www.mediswitch.co.za