122 lines
5.5 KiB
Plaintext
122 lines
5.5 KiB
Plaintext
A LOW COST PERFORMANCE BOOST FOR YOUR 386 PC
|
|
|
|
If you own a 386 based PC, you may be a little envious of the owners of all
|
|
these speedy new 486 based PCs. I know that I was. I say WAS because I
|
|
now get 486 class performance out of my old 386 system and I did not
|
|
spend a fortune. If you have a 386 system you may also be interested in
|
|
this upgrade.
|
|
|
|
THE Cx486DLC
|
|
|
|
Introduced in the summer of 1992, Cyrix produces a processor called the
|
|
Cx486DLC. The Cx486DLC is a cross between Intel's 386DX and 486SX. The
|
|
Cx486DLC is pin compatible with the 386DX and instruction set compatible
|
|
with the 486SX. Like the 486SX the Cx486DLC contains an internal cache
|
|
and an optimized execution unit. The cache and optimized execution unit
|
|
are the main reasons that a 486 is faster then a 386 at the same clock
|
|
rate. By replacing your 386 CPU with the Cx486DLC you get 486 class
|
|
performance without replacing your PC.
|
|
|
|
To be sure that your PC is upgradable to the Cx486DLC, check through the
|
|
following:
|
|
|
|
1 - The PC must be based on a 386DX (sometimes called a 386 or 80386)
|
|
from Intel or AMD. PCs based on the 386SX can not use this upgrade.
|
|
|
|
2 - Remove the cover of your PC and locate the CPU. It is a 1.5 inch
|
|
square IC. It should be labeled Intel or AMD 386DX. There must be
|
|
about 2 inches of open space above the CPU. The Cx486DLC runs hotter
|
|
than the 386DX and typically requires a heat sink mounted on top of the
|
|
chip. The additional space is required by the heat sink.
|
|
|
|
3 - You should have a socket on the motherboard for a 387 math
|
|
co-processor. You may have a 387 already installed.
|
|
|
|
If your PC meets all of the above requirements you can perform the
|
|
upgrade. I checked around for the best prices on the Cyrix chips and
|
|
found that CompuAdd express offers the best deal. They sell upgrade
|
|
kits for their line of scalable PCs. Each upgrade kit includes the
|
|
Cx486DLC, a Cyrix math co-processor, the heat sink and a chip puller for
|
|
removing the old 386 CPU. While they are intended for use with
|
|
CompuAdd's line of PCs, they are ideal for our upgrade and are quite a
|
|
bargain. At the time I'm writing this, the price of a 33 Mhz upgrade
|
|
kit has just dropped to $159 and a 40 Mhz kit has dropped to $249. A
|
|
math co-processor alone costs about $100. The upgrade kit to order if
|
|
your PC runs at 33 Mhz or slower is the 433DLC. The 40 Mhz kit is the
|
|
440DLC.
|
|
|
|
PERFORMING THE UPGRADE
|
|
|
|
Remove the cover from your PC, locate the 386 CPU. Note the location of
|
|
pin 1 on the CPU. Pin 1 is marked by a dot or cut off corner on the
|
|
chip. Use the chip puller to carefully pry the CPU out of it's socket.
|
|
Work slowly around the chip as to not bend any of the pins. Place the
|
|
486DLC into the socket with pin 1 in the same orientation as before.
|
|
Carefully press the chip into the socket. Once the chip is in place,
|
|
power on the PC, it should beep and power up normally. Power down the
|
|
PC, install the heat sink on top of the Cx486DLC and install the math
|
|
co-processor as instructed in the manual for the PC (you may need to
|
|
move a jumper in addition to installing the chip). Replace the cover
|
|
and you are ready to go. The PC should now run normally. To get the
|
|
full speed increase you will also need a program that activates the
|
|
Cx486DLC's cache. I've written such a program, called CYINIT. You
|
|
download a copy of CYINIT (in the archive 386486.ZIP) from both
|
|
Compuserve or Genie. It is in the IBMAPP section on Compuserve and in
|
|
Don Lancaster's PSRT on Genie. If would like a copy on disk, I will
|
|
provide one if you send me a check for $10.00. Once the system is up
|
|
and running add CYINIT to your autoexec.bat file. That way the cache
|
|
will automatically be activated when you start your PC.
|
|
|
|
THE PERFORMANCE IMPROVEMENT
|
|
|
|
I've upgraded several systems and found that the CPU performance
|
|
typically improves about 50%. Figure 1 shows the typical improvement
|
|
shown in the ZD Labs benchmark tests. The system upgraded was a 33 Mhz
|
|
386DX with a 64 K external cache and an Intel 387 math coprocessor (also
|
|
called an FPU - Floating Point Unit). The performance improvement varied
|
|
with the different tests, but averaged out to about a 50 % improvement.
|
|
The FPU test also showed that the Cyrix math coprocessor offered a large
|
|
speed gain over the Intel math coprocessor. Figure 2 compares the
|
|
performance of a 33 Mhz 386, a 33 Mhz Cx486DLC, a 33 Mhz 486DX, a 40 Mhz
|
|
Cx486DLC and a 66 Mhz 486DX2 running the 386 instruction mix from the ZD
|
|
Labs benchmark. As it shows the 486DLC gives 486 class performance to
|
|
your old 386 PC at a bargain price.
|
|
|
|
RESOURCE LIST
|
|
|
|
Cyrix
|
|
2703 North Central Expressway
|
|
Richardson, Texas 75080
|
|
|
|
In my article on upgrading your 386 PC to a 486. I recommended CompuAdd
|
|
Express as the best place to purchase the upgrade. Just recently
|
|
CompuAdd has shutdown the Express division and the upgrade kit is no
|
|
longer available from them. In scanning through the Computer Shopper I
|
|
have found the following list of vendors that sell the Cyrix CPUs ( I
|
|
have have not dealt with any of these outfits so these are not
|
|
endorsements on my part):
|
|
|
|
Buffalo Products 1-800-345-2356
|
|
|
|
L.A. Trade 1-800-433-3726
|
|
|
|
Nevada Computer 1-800-892-2928
|
|
|
|
Treasure Chest 1-800-677-9781
|
|
|
|
PC Importers 1-800-886-5155
|
|
|
|
In addition the Cyrix distributors are:
|
|
|
|
Bell Micro Pro 1-800-955-1999
|
|
|
|
Bell Industries 1-800-BUY-BELL
|
|
|
|
I hope that these numbers could be published in the next edition to aid
|
|
those looking to upgrade.
|
|
|
|
Robert G. Brown
|
|
30 Wicks Road
|
|
E. Northport NY 11731
|
|
|