Mylex 80486 EISA Motherboard and MS-DOS 5.0/6.0/6.2 (77178)

SYMPTOMS

If you have a Tangent machine with a Mylex 80486 EISA motherboard, you may experience erratic behavior when using Microsoft MS-DOS version 5.0 or 6.0, especially when using the Mylex DCE cache controller.

Symptoms include the following:

Machine stops responding (hangs).
You can't access directories.
You can't access the hard drive.
Your file allocation table (FAT) may be corrupt.

The following application-specific problems have also been experienced with this configuration:

With MS-DOS 5.0 or 6.0 and Windows 3.0, erratic inability to find COMMAND.COM when exiting Windows.
With Edit, QBasic, and 101-key keyboards, dedicated cursor keys operate as if the SHIFT key has been pressed (that is, they select blocks rather than moving the cursor).
With EMM386.EXE, when attempting to use CTRL+ALT++ or CTRL+ALT+- to change the processor speed, an
ILLEGAL INSTRUCTION : SYSTEM HALTED
error occurs. The only way to recover from this error is with a cold boot.
When running Memmaker from MS-DOS 6.0, the following error message is displayed:
Illegal Instruction Trapped

RESOLUTION

Mylex has confirmed this to be a problem with the Mylex 80486 EISA motherboard. In addition, Mylex has confirmed that the Northgate/Mylex 80486 EISA motherboard with BIOS version 6.04q is not compatible with EMM386.EXE. The newest revision is 6.15, which is compatible with EMM386.EXE.

Contact Mylex for additional information or a BIOS upgrade.

The product included here is manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding this product's performance or reliability.