USB Host Side Issues

To achieve proper USB connectivity six basic system elements must be present and working correctly.

1) Support from the BIOS

2) Support from the Operating System

3) Physical USB ports

4) A USB Device

5) The correct USB cable for the device

6) Drivers either from the OS and/or the peripheral maker

Does my Computer Support USB?

There are two programs available to check if your system is USB ready. Although, neither of these programs is a guarantee that your computer will provide trouble-free USB, both provide good indications of capability.

Intel USB Check
Entrega USB Ready

Identify the USB Host Controller

All USB host controllers are NOT created equal. You should identify the USB host controller type so that you will know how to proceed if you have problems. For a “How To”, go here:
Host Controller PCI / USB - How to identify - Win9X

Cleanup the Device Manager / Windows Safe Mode

From initial installation problems to suddenly not working USB, cleaning up the Device Manager in Safe mode is the first step in Win9X troubleshooting. Many hardware related problems in Windows can be traced to ghost and/or duplicate device entries. Obsolete and/or duplicate devices can ONLY be seen and removed from the Device Manager while in Windows Safe Mode. For a good “How To”, see here:

Clean-up Device Manager in SAFE MODE - Win9X

BIOS Settings

Common BIOS Problems

Many USB Problems are the result of improper settings in the BIOS. To achieve proper USB connectivity the BIOS needs to be a properly working partner.

Enable USB in the BIOS

USB is often disabled by Default in the BIOS. To enable USB in the BIOS one or more of the following statements must be true.

USB Keyboard - DOS or Enabled (Even if you have NO USB Keyboard)
Legacy USB Support - Enabled

Assign IRQ for USB - Enabled (Some combinations of OS and BIOS version require this setting to be Disabled).

If there are NO references to USB in the BIOS setup, your BIOS Version Needs To Be Updated.

The BIOS version does NOT support USB.

Vintage 1996-97 motherboards, even those with USB pinouts (AT Style) almost always require a BIOS update to achieve proper USB connectivity. Generally, a BIOS date of June 1998 or newer is required for Win9x systems. A BIOS date of October 1999 or newer is usually required for systems running Windows 2000. New Operating Systems require new BIOS revisions.

BIOS Help Links

BIOS Agent - Free Software Reports Your BIOS Details and Configuration
BadFlash - Good Information and Help
CTBIOS - Small DOS program that identifies the BIOS and motherboard - Program is in German but, you'll get the idea
Wim's Bios Page - BIOS Help Site
USBMan BIOS Download Site - Listed by Manufacturer
Improperly updating the BIOS can render a system inoperable and unbootable. Follow ALL manufacturers instructions carefully when updating the BIOS. Clear the CMOS with the jumper (see manual) and reset all BIOS data before rebooting to Windows.

BIOS settings Effecting USB

BIOS settings that effect the operation of Universal Serial Bus are shown optimized for USB. The most common BIOS settings that effect USB performance are:


Reset the FSB to Default

Aggressive memory settings (Turbo/Fast)

Reset to Normal or Default

Lack of usable IRQs

Com1 and Com2 can be disabled if not used, allowing the OS to use these IRQs for other devices.

Plug and Play OS – Disabled

* Older Win9x (Socket 7 based) systems may require this option to be Enabled to allow Windows controlled IRQ Steering to operate correctly. Toggle ON or OFF as your system requires.

IRQs Assigned – Auto

Power Management – Disabled

* The Operating System should control Power Management.

ACPI - Disabled

* ACPI enabled in the BIOS is the source of many USB problems. If you are having problems with USB, ACPI should be disabled. Unfortunately, simply resetting the switch in the BIOS may not be enough. Normally, a reinstall of the operating system will be necessary. Remember to backup your data before you reinstall the OS. I recommend a clean install to a newly formatted hard drive.
USB Keyboard – Enabled or DOS