Virtual OS/2 International Consumer Education

April 1998


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OS/2 Technology Issues.
First in a series.

By: Dan Casey (

Welcome to the first installment of, what I hope will be, a continuing series of articles and discussions on OS/2 Technology issues. With more and more hardware vendors taking the easy path to developing and manufacturing products to Microsoft's specifications, Compatibility in the OS/2 environment is becoming a bigger issue.

The facts presented, here, are based on my own research and personal experience, and thus, cannot possibly cover all of the different choices available (I do have a "Real Life" and a real job). So, after reading this article, if you have any additions, corrections or comments, you can e-mail me at and the next article will incorporate readers comments, suggestions, additions and corrections to this article.

Part 1
Choosing a Motherboard.


This is an area with many different choices. Seems that everyone (and their brother) is building and marketing motherboards these days. The big question is: Which one is the best? Or, more appropriately, which one is the best for you?

The answer is: There is no simple answer. Every user's needs are different.
So, how do you choose?
By being informed. By knowing the options available to you, and what these options are capable of.

Step 1
Which CHIPSET do I use?

Without getting into too much technical detail, I'll outline the basics.
Many users don't realize that all chipsets do not cache memory above 64meg. ( I didn't). But, if you intend to install more than 64 meg of RAM on the system board, you need to know which chipset is capable of caching all that ram. OS/2 addresses RAM all at once. It doesn't know from base, upper and extended RAM. So, you'll want to make sure that the system board and chipset in you system is capable of caching all the RAM you have installed.
This article is limited to Socket 7 Chipsets (Pentium class). Pentium II chipsets are not included, as the max cacheable RAM areas are higher than 64 meg.

INTEL Chipsets. (HX, VX and TX)

TX and VX chipsets are not capable of caching more than 64 meg of RAM.
The Busmastering (UDMA) IDE drivers in OS/2 support these chipsets.
I don't recommend these chipsets simply because of the max cacheable ram area limits. However, they do work with the Busmastering (UDMA) drivers from IBM (IBM1S506.ADD).

The HX chipset is capable of caching up to 512 meg of RAM, provided the Cache Module is at least 512k, and contains 2 TAG RAM chips.
The Busmastering (UDMA) IDE drivers in OS/2 (IBM1S506.ADD) support this chipset.
This chipset is no longer manufactured by Intel. But Motherboards do exist with this chipset.

VIA Chipsets

For detailed and complete information on these chipsets, look at the Chipset Comparison Guide
Max cacheable are of RAM: 512 meg or 1 gig.
The Busmastering (UDMA) IDE drivers in OS/2 (IBM1S506.ADD) do NOT support these chipsets.
VIA does have BETA level drivers available for OS/2, but continued development is, at this time, not guaranteed.
According to Sam Detweiler, VIA is unwilling to provide Tech Support to the IBM OS/2 developers beyond what the VIA Manuals offer.
Based on Personal Experience,If you are running with a SCSI disk subsystem, I can recommend these chipsets.

SiS Chipsets

Information on the SiS chipsets is not as easy to come by. The website returns an error when attempting to view the documents, and the downloadable versions are in MS Word format. But here's what I found.

5571 Chipset

Unknown max cacheable area. Features list 2 programmable non-cacheable areas of RAM, but max cacheable area not defined.
75/66/60/50 Mhz bus speeds
Supports 256k and 512k Pipeline Burst Cache
2-348 Meg system RAM
OS/2 Busmastering drivers available.

5591 Chipset

Will cache up to 256 meg of RAM.
Supports 256k, 512k or 1 meg of Pipeline Burst Cache
2-768 meg system RAM
OS/2 Busmaster drivers available.

An EXCELLENT source of information on PCI Chipsets is available on the Web. It's known as Tom's Hardware Guide, and contains a more detailed synopsis of the various Chipset's features.

As I stated earlier, every user's needs are different. This series of articles is not about specific recommendations. It's about keeping you, the user, informed about the various hardware technologies available, and how they all fit in with an OS/2 system.

I sincerely hope that it helps each of you in your decision-making process. If there are any additions, corrections and/or comments, feel free to send them to me. I'll include them in next month's issue of the VOICE newsletter.
Dan Casey
Vice President, VOICE.


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