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So, you want to get into desktop video, maybe you’ve already got a PC, but should you upgrade, or replace? Rick Maybury puts his expansion cards on the table



Buy a vacuum cleaner, TV or VCR today, and barring breakdowns, you can reasonably expect it still to be doing the job it was designed to do in five to eight years time. Unfortunately the same cannot be said of a new PC. The pace of processor development is such that it will be virtually obsolete before it leaves the shop, and worth a fraction of what you paid for it in a couple of years time. The good news is that it will probably still be working just fine...


The trouble is, a state-of-the-art PC brought five years ago for £1500, is incapable of running most of today’s high-powered applications, and in desktop video terms, it is almost worthless. Or is it? In fact 386 and 486 PCs still have a useful role to play, running simple camcorder edit control and title generator software (with a VGA to video output device or genlock), but realistically that’s about as far as you can go, without spending some serious money on upgrade components, or a new machine.


In theory it’s possible to upgrade even the earliest IBM compatible PCs to a high-performance multi-media specification, though the only parts that would be left from the original are the case and the keyboard. The decision to upgrade, as opposed to buying a new machine, is a tough one, but the plain fact is, if you want to use the very latest desktop video hardware and software, and stay ahead of the game for a year or so, then you have little choice but to bite the bullet and buy a new PC, though you will have the added advantage of a pre-installed operating system, bundled software, extra hardware and a manufacturers guarantee.


If your present PC and aspirations are more modest, then upgrading becomes a viable alternative, but where do you start? Basically there are four key components in a PC, that determine power, speed and capacity, and ultimately its suitability for desktop video. They are the central processor (CPU), the main board or motherboard, the amount of random access memory or RAM, and the size of the hard disc drive. Upgrading one or all of them will make a difference, but you have to decide how far you and your budget can go.



The cheapest and simplest way of making a PC run faster and more efficiently is to increase the size of its RAM, though there are limits, and it can do nothing to improve actual processor power. Memory prices have fallen dramatically in the past two years, and despite scare stories about imminent price rises, it remains the single most cost-effective upgrade for the vast majority of PCs.


Dynamic random access memory (DRAM) chips are mounted  on small printed circuit boards, called SIMMs (serial in-line memory module) or DIMMs (dual in-line memory module), with 30, 72 or 168 pins (though the latter is only used on the very latest PCs). They’re located in ‘banks’ of sockets on the motherboard. Adding new memory modules is actually quite easy, though if you haven’t had the lid off your machine before, or you don’t fancy the idea of poking around inside, you may want to have it fitted by an engineer.


However, before you do anything you must know the type and configuration of memory your machine can use. This will normally be contained in the operating instructions, or motherboard manual that should have come with your PC. The first thing to determine is which kind of module you can use. Most 386 motherboards only accept 30 pin SIMMs; 486 mainboards often have both 30 and 72 pin sockets. Pentium-compatible boards generally have 72 and 168 pin sockets. Secondly the type of memory is important, there are two main parameters: parity, and speed. It is possible to mix different types (i.e. use parity memory upgrades with existing non-parity RAM, but not the other way around), though it is generally safest to upgrade with the same sort that you already have. Faster 486 and Pentium machines also have the option of using EDO (extended data out) RAM, and it’s important to use the same type.


It is difficult to generalise about memory configurations but it is usual for the upgrade to double the size of the PC’s RAM. For example, if your machine has 4Mb of RAM, the next logical step would be 8Mb; 8Mb increases to 16Mb, 16Mb to 32Mb, and so on. Companies selling RAM modules will normally talk you through the selection procedure, so it is helpful to have the make, model, type of PC and processor and if possible, the name or type of motherboard to hand when ordering.


If all the available slots on the motherboard are populated you may be able to part-exchange old modules for new ones, or use an expander socket, which has slots to use your old boards, combining them into one SIMM or DIMM.


Memory chips can be damaged or destroyed by static discharge so they should be handled with care. Do not remove them from their protective packaging until you have first discharged yourself by touching the PC’s metal chassis. (The PC should always be disconnected from the mains before you delve inside, unearthed metalwork will still dissipate a static charge). If the sockets are obscured by cables move them gently out of the way, or better still make a note of where they go, and remove them, so you can get at the sockets. Memory boards usually fit only one way around, so observe the position of notches in the connector strip. On most sockets the boards slide in at an angle, and snap into position as they’re tipped towards the vertical.


Replace the leads, and the cover and switch on. You may get a warning message from the BIOS at boot-up, but the machine should automatically recognise the new memory and ask you to accept the updated configuration. Check the memory test report, after boot up, to make sure the RAM is properly installed, then sit back and watch it fly.  



CPU upgrades are the next most effective performance upgrades, though it is really only worth doing on better-specified 486 and low-end Pentium models, and you may also need extra memory to get the most out of it. How far and how fast you can go will depend on the design of the motherboard but it is possible to achieve Pentium-class performance on a 486 for around £100, which is a good deal less than installing a Pentium motherboard and processor.  However although it will enable you to run Windows 95 at something like a decent speed and many software packages will run a lot faster, it will do little for the latest desktop video applications, which depend on the full spec Pentium chip architecture and motherboard bus systems. 


The economics of a straightforward Pentium upgrade are a little easier, and depending on the motherboard facilities, it is possible to replace a Pentium chip with a faster model, up to and including the most recent 200MHz MMX versions, which are eminently suitable for high-end DTV applications..


The same general precautions apply in a CPU swap as a memory upgrade, including disconnecting the mains supply, and ‘earthing’ yourself on the chassis, before you touch anything. Next, locate the processor, or empty overdrive socket, in the case of some 486 boards. Most processor upgrade kits come with CPU removal tools, to make the job easier. Many motherboards have what’s known as ‘zero insertion force’ or ZIFF sockets, these usually have little levers on the side, to release the chip. Once the old CPU has been taken out the new one can be fitted, remembering to observe the correct orientation. The new CPU can often be a good deal bulkier than the chip it is replacing and may be fitted with a heatsink and on-chip fan, so make sure there’s plenty of room around the processor, for cooling air to circulate, and that the leads do not obstruct the fan. It may also be necessary to change jumper settings on the main board, install additional software or make changes to the PC’s BIOS, but these relatively simple procedures are normally clearly outlined in the instructions.  



In many cases a CPU swap only delays the inevitable and at best is only a stop-gap solution. It is usually far better to change the motherboard as well, especially if the old one is more than a couple of years old. Most mother board conform to the IBM AT standard and will fit most cases,  but do check before you buy, especially if your machine is made by one of the big-names, who may use their own proprietary main boards.


Motherboard swapping looks more difficult than it is but if you approach it in a systematic manner, it needn’t take more than an hour or so. It’s always a good idea to establish a fail-safe position before you begin, so that if it all goes horribly wrong, you can at least get back to where you were. Make a sketch of where all the boards and cables go, or better still, take a colour photograph of your PCs innards. Make a note of where the switch and display leads go, the connectors are usually marked.  Remove all of the cables and expansion boards, you should then be able to locate the one or two screws holding the board into the case. Once they out you should be able to slide the board out. If necessary unlatch any supporting pillars with a pair of long nosed pliers.


Replacement is a reversal of the removal procedure, though you may need to re-position the supporting pillars, to align with the holes on the new board. Once it is secure you can re-fit the power, switch and display cables, memory modules, the old expansion cards, and any new ones. If you’re moving up from a 486 to a Pentium you will probably want to replace the old ISA graphics card with a faster PCI bus type. You probably won’t need your old IDE drive card as most recent motherboards have the disc drive electronics and connectors on board. The new board will have to detect and configure itself to the disc drives, but this is normally carried out automatically by the board’s BIOS system, when it is switched on for the first time.



Whatever upgrade path you choose, one thing is certain, sooner or later you will need a larger hard disc drive. Buy the biggest, fastest drive you can afford; if you’re building a high-end system it is worth spending some time on the various high-performance options -- see the in-depth feature on hard discs in issue one of Computer Video.


Hard drive upgrades are generally quite simple. The easiest method is to slave the new drive to the existing one, there should be a label indicating appropriate jumper settings on both drives. This is also quite useful in DTV applications, where the new drive can be dedicated to storing large video files. Slaving the new drive is also an easy way of moving lots of files over to the new drive, prior to retiring the old one.


Standard HD drives are normally held in place by four screws, and connected by two or three cables, one for power, one for data, and possibly one for the HD activity light on the front panel. Once the swap has been completed the BIOS will need to detect and configure the new drive, install the operating system and application and you’re in business.





* Buying new is generally preferable to upgrading, you probably won’t save a great deal of money, moreover a new machine will come with bundled software, and a warranty!


* Often, by upgrading you will expose shortcomings in another area, so don’t expect simply to replace just one component


* If you don’t feel competent to upgrade your machine don’t take risks, pay to have the modifications done by an engineer


* Whatever the upgrade observe sensible precautions, like disconnecting the machine from the mains before you start work, and discharging yourself, before you touch any static-sensitive components


* When adding extra RAM make sure it is the correct type, parity and speed, consult your manual, before you buy


* If you run out of spare RAM sockets you can still use your old modules by using expander cards


* A 486 to ‘Pentium’ CPU upgrade is really only a stop-gap measure, it is far better to buy the processor and motherboard together, which should also ensure they are configured correctly


* The commonest cause of apparent hard disc failure is incorrect setting of jumpers


* Make sure your case will accept a standard AT type motherboard, some PC manufacturers make their own non-standard boards, that cannot be easily updated or replaced


* If you’re on a very tight budget you may be able to part-fund the upgrade by selling retired components in magazines like Micro Mart




Ó R. Maybury 1997 1905



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