IRQ 5 Conflicts With HIMEM.SYS When Using Invisible LAN Disk Cache

We have determined that you can't use IRQ 5 for the network adapter if you're running HIMEM.SYS and the Invisible LAN disk cache.

Problem Description

The problem occurs when all three of the following conditions are met:

• The network adapter is set to use interrupt level IRQ 5, and
• HIMEM.SYS is installed, and
• The Invisible LAN disk cache is installed.

In this case, the computer crashes.

Analysis

The problem occurs because HIMEM.SYS hooks the IRQ 5 interrupt vector. (The IRQ 5 interrupt vector is also the General Protection interrupt vector, which must be hooked when accessing extended memory.)

If the network adapter is set to use IRQ 5, then the Invisible LAN disk cache also hooks IRQ 5, which creates a conflict between the disk cache and HIMEM.SYS.

Solution

To solve the problem, you must do one of the following:

• Set the network adapter to use a different interrupt level (this is the recommended solution), or

• Remove the Invisible LAN disk cache (you can use SMARTDRV instead), or

• Remove HIMEM.SYS if you don't need it.

Notices: Copyright 1997 by Invisible Software, Inc. Invisible Software and InvisibleLAN are trademarks of Invisible Software, Inc. Other trademarks are the property of their respective holders.

This document was prepared on 01/30/97, and was believed to be accurate as of that date. Procedures, specifications, and compatibility may change without notice, and therefore this document may be out-of-date and/or inapplicable to current product versions. Invisible Software provides this document "AS IS" and without warranty of any kind. Under no circumstances shall this document be construed as creating or expanding any warranty of product performance.

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