Sidebar -- What Makes A Difference
by Donald Jenner

Brett Glass is probably one of the most talented hardware wizards in Silicon Valley.  In his Infoworld column awhile back he commented that he had no intention of moving from his trusty 486DX/2-66mHz machine to a Pentium until a Pentium could be had at 150mHz.  Just about that time, Intel announced a 133mHz part -- close enough.  But that misses the point: Processor speed is necessary to a speedy system; it is not sufficient by itself.

Take a hot processor, but feed it data across an old-style ISA bus and front-of-screen performance -- what you see happening -- can slow almost to a crawl.  Take a more modest processor and put it on a well-designed motherboard (older systems with IBM Microchannel Architecture or EISA architecture are good examples) and the result can be.  Couple that with a fast hard disk and a really zippy level-two cache, and it is possible that the more modestly based system will out-perform the one with the really hot chip in the middle.

The other side of this coin is also important:  Putting a hot new chip in a computer of older design by way of an upgrade may prove disappointing.  All those other elements -- slower bus, slower hard disk, memory constraints and so on -- will conspire to throttle performance.

So, what can you do if a new system is not in the cards, but you need more performance now?  There are some options that cost relatively little, and will extend system life.  This is no sow's-ear-to-silk-purse story; we are talking stop-gap measures.

Memory should be a high priority.  The more you have, the better.  This is particularly true if you are running on commodity-type hardware -- Macs and PC-family machines.  The newest OSs for these machines, such as Microsoft Windows 95, manage memory effectively.  There is a caveat in this: Many older machines boasted of being able to manage 32mb or even 64mb of system memory; this was true, but at anything beyond 16mb, things got very, very sluggish.  The rule of thumb seems to be, if you have an ISA-bus machine, you are probably constrained as to how much memory you can access efficiently.

There are also some interesting processor-upgrade options for PC-family machines -- interesting because they are relatively inexpensive.  For example, Kingston Technology and Evergreen Technologies both offer a number of options for different classes of systems, ranging in price from US$275. to US$300..

In 486 machines, these can boost system performance to Pentium 75mHz levels -- again, depending on other constraining factors.  Using AMD clock-tripled 486-class processors running at 100mHz or 120mHz, with substantial onboard level-one cache memory and other speedup tricks, these are plug-and-play upgrades.

Since the AMD clock-tripled chips are 3.5 volt parts, these new chips are supplied mounted on a small circuit board that does the voltage regulation; they also come with a heatsink/fan combination built in.  [This could be a problem if your system's main processor is hidden under a close-fitting hard drive; check before you buy.]

Is this is a good move?  First, consider the numbers:  A current well-designed Pentium-class PC-family machine, with a fast display system and a fast, SCSI hard disk system and lots of memory -- the kind of machine one buys for graphics performance, not office automation -- costs somewhere between US$4,000. and US$5,000..  Assume an older graphics-spec'd 486-based system (DX, 33mHz or 50mHz) with 8mb of system memory and decent hard disk performance.  Adding memory and a processor upgrade will cost between US$700. and US$1,000..  The upgrade will add two years to the old system's life, or at least make it a good second seat; the new system will have a reasonable life of three, but probably not four, years.  At the very least, the upgrade cost over its effective lifetime is something like half the annual cost.  Moreover, the cost to try the upgrade is low enough that you expense it.

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