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COMPUTER BITS By JENNIFER BONNITCHA Speeding up your PC Is the trend towards bigger/newer/faster computers starting to get you down? Are you one of the early PC owners worried that you are getting left behind in the speed/storage race? Fortunately, there are several alternatives to "junking" your old PC and moving up to the more expensive models. the options store many programs and the associated data files. In addition, the time saved in shuffling discs into and out of the drives can be quite significant. If your software uses the disc drive intensively, your best bet is a fast hard disc with around 28 milliseconds access time. Cache memory There are many ways to help you catch up to the leaders. You can use hardware products to add to a low-end computer's memory, or increase its computing power. Or you can use better software. Some companies, such as Borland International with its Quattro spreadsheet, take an alternative approach by designing software which is very powerful and yet tolerant with disc storage and memory requirements. Other programs like Mace and Norton Utilities give you the ability to fine-tune your computer system. It used to be so easy. A PC came with a maximum of 51 ZK memory and all programs could easily run within this limit - you even had enough left over to run memoryresident programs like SideKick. As times changed and the much faster, more sophisticated programs required more memory, it became obvious that something had to be done. Apart from the obvious enhancement of more memory, for around $350 you can buy a hard disc drive to accommodate programs too large for standard floppy discs . A hard disc has enough room to You could try using disc caching software which sets aside a portion of RAM as a temporary storage area - or cache. This means that when a call is made by the software for data, the cache software intercepts the call, locates and passes the data to the program, and stores as much as will fit in the cache. Should the program require the same data again, it is available immediately. Interestingly, as you work, the program continues to monitor the data required and places as much as possible in the cache, even if it was not the most recently used - smart eh? It should be apparent that a program this clever could help speed up even the slowest application. Typically the cache is used when dealing with very large data files such as those generated by database and spreadsheet programs. RAM discs ONE WAY OF SPEEDING UP your PC or PC XT is to add an accelerator card with its own 80286 or 80386 microprocessor. You just remove the cover and install the board according to the supplied instructions. This 286 accelerator card from Electronic Solutions runs at 8MHz. 70 SILICON CHIP Another alternative is the RAM disc (or VDISK with DOS 3). Using this technique, a portion of RAM is made to act as though it is a disc drive. You copy data into the RAM disc and access it just like the familiar hard disc. In this case, you decide what is available whereas cache software decides for you. The main advantage of the RAM ADDING A RAM CARD allows you to create RAM discs and use memory-resident utilities to speed up your work. This EEMS RAM card lets you expand the system memory by up to 2Mb. (Available from Electronic Solutions or PC Marketplace). disc is increased response time but the downside is that anything stored in RAM is subject to loss whenever power is lost to the computer. You still need to transfer data from RAM to a disc for permanent storage. A popular trick is to copy program overlays, dictionaries etc onto a RAM disc to speed up the operation of programs which make extensive use of overlays. Or how about an Accelerator card, which includes its own 286 or 386 microprocessor? Generally, you will experience increased speed from your ageing companion. You just remove the cover, add the board and hey presto, supercharged operation! Alternatively, you could opt for a faster processor chip. The original PC limped along at 4.77MHz to make sure all other parts of the computer system could keep up with the pace. To speed it up, the PC can make use of the NEC V20 and V30 processor chips. The V20 is for use in 8088 computers and the V30 in 8086. The main function of these chips is to speed up some, but not all, operations. Maths co-processor Speaking of processors, if you spend a lot of time dealing with numbers, you may consider a maths co-processor. This little chip slips comfortably onto the motherboard of almost any PC since most are manufactured with the empty socket. The 8087 maths coprocessor certainly speeds up number crunching activities like calculating square roots and drawing screen graphics in programs like computer-aided design (CAD). Most PCs run on some version of Microsoft's Disc Operating System (DOS). This system controls all basic operations for the computer so some developers have found ways to modernise this operating system. IBM recently released a new single user, multi-tasking operating system known as OS/2, also designed by Microsoft. Software is specially designed to take advantage of the OS/2 facilities in that each program is similar in operation, in much the same way as the Macintosh computers. DOS has now been endowed with some of the OS/2 characteristics through programs like DESQview and Windows which feature the increasingly popular graphical interface. Both these programs enable a standard PC to run several programs at the same time and work with larger amounts of memory than is usually allowed with DOS. Windows in particular is designed for the 286 machines and better, however it can provide the more powerful versions of 8086/8088 computers with some of the graphical interface. Another multi-tasking operating system option is Unix/Xenix, however these tend to work best on the 386 machines. Speed junkies can add memory and speed-up boards to their old PC workhorses, however it is important to understand a few basic principles. Expanded memory The original vanilla-flavoured PCs don't function particularly well with Windows and they certainly aren't capable of running the new OS/2 operating system. An alternative for machines with 8088 or 8086 processors is expanded memory which conforms to the Expanded Memory Specifications used by Lotus, Intel and Microsoft (sometimes referred to as LIMS memory). With expanded memory, you can obviously work with much larger data files but you can also use memory-resident utilities and RAM discs to speed up your work. Whenever the computer calls information from a disc, there is a delay while the operating system checks the File Allocation Table on the disc to determine the exact location of the data. Calling the same information from a RAM disc is astonishingly faster. If this sounds like the alternative for you, all you really need is an 8-bit expansion slot in your computer and a memory board which will fit into the case. ]ANUARY1990 71 Speeding Up Your PC - ctd THIS HALF-CARD will allow you to increase the RAM in your PC out to 640K. (Electronic Solutions & PC Marketplace). The AT-style computer released in 1984 features the 80286 processor running at around 8 to 10MHz. Once again, you can make use of the features mentioned above to really add some zip to your computing. Additionally, you can use DESQview or Windows/286 to run several programs at once and work with the larger amounts of memory. Finally, let's look at the 80386, which has memory management inbuilt. Should you feel the need to really zap along, you should add full-speed RAM to the mother board or in a 32-bit expansion slot. Addressing over 640K A generally little-known fact a bout the 8088 and 8086 PCs is the ability to address 1Mb of memory. Since the maximum addressable by DOS is 640K, the remaining 384K is used by the CPU iteslf to find data or instructions. From 640K to 768K is reserved for video drawing and re-drawing instructions. Hard disc controller ROM modules typically 72 SILICON CHIP use from 768K to 896K, while the PC's own ROM will address from 896K to the 1024K (1Mb) limit. But no matter how hard you try, you can't use the top 384K of memory using DOS. Sometimes, on AT-style computers, the additional memory is used as "shadow" memory. A copy of the ROM BIOS is loaded into RAM for increased performance. Shadow RAM can also enhance the screen refresh on EGA monitors. While the 8088 addresses 1Mb of RAM, the 80286 can address up to 16Mb and the 80386 a staggering 4 Gigabytes (ie, 4,096Mb)! While the space below 1Mb is used by various sections of the computer, the space above 1Mb is reserved purely for extended memory. It is here that operating systems like OS/2 and Unix use the additional space for vastly increased computing power. However, whenever the 286 or 386 computer runs DOS, it has the same problems as the 8088 - the 1Mb address limit. Extended memory lets DOS use 64K to bring it up to 740K. Windows/286 supports this added extra. Users of the 80286 and 80386 machines can actually choose between expanded or extended memory. When considering the purchase of a memory board, you should aim for a board with supports a variety of configuration options - conventional, extended and expanded (preferably with software rather than hardware selection for ease of use). Extended memory is typically used for programs such as OS/2 and Unix since they require a fair amount of room to move. But as far as DOS is concerned, extended memory is really a dead end. Expanded memory on the other hand provides a much greater data space and manages multitasking sessions. The increased data space means you can create larger spreadsheets and move your utility programs to expanded memory. It relies on a feature known as "paging". A "window" within the visible memory area (1Mb on the 8088) is swapped to different areas or "pages" within the expanded memory. Thus the CPU is fooled into operating within the virtual area created by expanded memory. Above 784K, there is 64K of empty space in an unused memory gap. Expanded memory can therefore create a page frame to hold at least four 16K pages. By managing the CPU requests, the memory manager can map any 16K segment within expanded RAM into any of these pages. None of this happens automatically. Expanded memory relies on both the hardware and software working together. A combination of extra RAM, memory mapping hardware on the board and a device driver in your CONFIG.SYS file all work together to let your applications and DOS recognise the paged memory. So the moral of the story is that those programs that work well at the low end of the computing scale perform even better at the high end on the more powerful machines. But as long as there are ways to keep these older computers kicking along, the plug need not be pulled on low-end boosters. ~