🚀 go-pugleaf

[Follow up set to comp.os.ms-windows.win95.misc]

In article ID <4ebic1$rrt@agate.berkeley.edu>, kchsieh@uclink4.berkeley.edu
(Kai Hsieh) writes: 

>You can NOT use COM4 (COM1 or COM2 is still questionable).  

Huh? There is nothing questionable about using COM 1 or COM 2 for ANYTHING. 
The reason you can't use COM4 is an addressing conflict. 

>The reason that I got from Dell's technical support is Window95 will 
>behave very strange, if I don't use COM3, and IRQ4.

Someone does not know what they are talking about. If your modem is an
internal, you need to disable COM 1 or COM 2 on your controller. Quite
simple, and nothing "very strange". 

>With some investigation of myself.  The real answer I believe is
>hardware-conflict between the graphic card and COM4.

No, it's an addressing problem.

>For a detail explanation, take a look at the following www site:
>"http://www.castrop-rauxel.netsurf.de/homepages/mschoebel/faqmode"
 
Better yet, read this from Orchid Tech Support:
-----------------------------------------------
First a little background explanation.  The Fahrenheit doesn't
use a COM port or IRQ4.  The S3 chip on the Fahrenheit uses some
high numbered 16 bit I/O port addresses for some of the
accelerated functions.  It turns out that some 8 bit devices that
users have in their computers, (like serial ports, and sometimes
network boards, modems, etc.) don't understand 16-bit I/O
addresses.  They truncate the address to the number of
significant address digits they understand.  So if the S3 chip is
using say 92e8, the 8-bit device only sees 2e8.  This is the
nature of the conflict, it has nothing to do with IRQ's, and is
common to, but not unique to COM ports, esp. COM4 which uses 2e8
by default.

We often see people using 8-bit devices  that don't fully decode
the 16 bit address the S3 chip is using.  If those devices (like
Serial I/O boards, and sometimes network boards) happen to be
using the I/O port address 2e8, that causes the 2 devices to
conflict.

The S3 enhanced command registers use the following default I/O
addresses (for accelerator functions)...

42e8  82e8  92e8  a2e8  b6e8  e2e8
4ae8  86e8  96e8  a6e8  bae8
      8ae8  9ae8  aae8  bee8
      8ee8  9ee8  aee8


There is an alternative set if I/O addresses you can program the
chip to use, but it has to be done at the driver level.  It's not
something that can be implemented by an end user.  I believe the
alternative set of addresses has a performance disadvantage.
That's why most of the S3 developers use them.  You don't mention
if you're a developer or not.   If you are, I would recommend
purchasing the S3 developers kit for more information.

Lisa Ayers  Orchid Technology Tech Support



Phil Leonard
pleonard@cybercom.net
73044.2615@compuserve.com
http://cybercom.net/~pleonard 

W95 PPP setup * UUdecode described * Pkunzip FAQ * W95 Disaster prevention