benderly@cs.columbia.edu (Dan Benderly) (06/02/89)
A freind of mine just got an old, 4.77 MHz PC Clone. I am looking for inexpensive ways to speed it up for her. I am aware of the V20, which replaces the 8088. Is there anything else that I have to do, besides unplug the 8088 and plug in the V20? Anyone know a particularly good place to buy a V20? Anything I should watch out for? Is there anything else I can do? Replace the crystal with a faster one? etc, etc. I am not afraid to get my hands dirty, but it has to be cheap, and not take TOO long. Thanks!!! Dan benderly@cs.columbia.edu P.S. If people wish to E-Mail instead of post, I'll summarize, if there is interest.
bcw@rti.UUCP (Bruce Wright) (06/03/89)
In article <230@cs.columbia.edu>, benderly@cs.columbia.edu (Dan Benderly) writes: > A freind of mine just got an old, 4.77 MHz PC Clone. I am looking for > inexpensive ways to speed it up for her. > > I am aware of the V20, which replaces the 8088. Is there anything else that > I have to do, besides unplug the 8088 and plug in the V20? Anyone know a > particularly good place to buy a V20? Anything I should watch out for? > > Is there anything else I can do? Replace the crystal with a faster one? etc, > etc. I am not afraid to get my hands dirty, but it has to be cheap, and not > take TOO long. You don't have to do anything special to replace the 8088 with a V20. If the machine is that old it's possible it has some older software on it that may need adjustment to deal with the increased speed of the V20 (though the problem is not as severe as putting that sort of software on a 286 or 386). Not very likely to be a problem these days though. The speedup for a V20 for most applications is about 10-20% (some salespeople will try to tell you it's more like 30-35% but this is only for rather specialized applications). Still, it's not bad for under $10. Since you don't mention your experience with electronics and your question doesn't sound like one likely to be asked by an expert, I probably should mention that you need to make *real* sure that you put the V20 into the socket with the notch facing the same direction that the notch on the removed 8088 faced ... the socket is normally labelled with a notch of its own. Putting a chip in backwards is a good way to fry things! Also, be pretty careful about putting the chip into the socket - it's possible to bend or break the pins. You do normally need to apply a certain amount of force, just be sure that all the pins are properly aligned and don't overdo it. It's also pretty easy to bend or break pins as you remove the old chip (which you probably don't want to throw away immediately). The only other reasonably cheap thing you can do is to replace the crystal. This is more problematic, because it may make the bus (or the motherboard!) too fast for some of the chips. You may want to look around for kits that will do this, because they will have more detailed instructions. For most clones, all you need to do is to replace the crystal with one a bit higher; you will probably have to experiment to find out how high your equipment will go. Most PC's have a certain amount of engineering margin (that way they don't have to do a lot of testing to find the limit of each box), and can run somewhere in the neighborhood of 6-8 MHz instead of 4.77. This is a VERY noticeable improvement if you can get it. Be aware that you will normally have to get a crystal which is 2x the rated MHz of the machine (it is divided down by the circuitry), at least if the machine is a strict clone. It's not difficult, but it requires more technical ability with a soldering iron than the first option (which requires none). You can also get an accelerator card (if you do this the above two options become irrelevant). But the cost is pretty high ($250 or so is the starting point and they go up from there), and all you wind up with is a fast PC (no protected mode Unix or OS/2 if that's important to you), unless you go with some of the *REAL* expensive boards with complete CPU and memory on a card.... to me, if you want the protected mode functions, it seems that you are better off (possibly even in dollar terms) to go with a real 286 or 386 machine, but the boards do sell pretty well. Good luck. Bruce C. Wright