Windows 95/98

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Windows 9X

A Brief History

This section will give you information on the various dates associated with Windows 95 and Windows 98 to help you determine which version of the operating system a customer has.

Windows 95
There are 4 versions of Windows 95: Windows 95 OEM, OSR 1, OSR 2, and OSR 2.1. OEM stands for Original Equipment Manufacturer, and is used to represent any hardware or software sold by a company such as Dell as opposed to purchased retail. OSR stands for OEM Service Release, and is a new version of the operating system for OEM venders for resale with new computers only. Customers cannot purchase OSR versions retail, nor may they be sent such and update for a previously owned machine.
The original version of 95 sent out by Dell was version 4.00.950, and has a date code of 0795 as it was shipped on July of 1995.

Note: You can find the version number of Win95 or 98 by checking the System Properties > General Tab. This is the best way to verify the Win9x version.

The differences found in the various OSR releases are discussed below.

  • OSR 1
    This version of Windows 95 contained fixes not present in the original OEM version of 95. It also contained a full version of the PIIX3 drivers on the CD.
    The version number of OSR 1 is 4.00.950 A, and the date code is 0196.
  • OSR 2
    The major upgrade in this version of 95 is the FAT32 support.
    The version number of OSR 2 is 4.00.950 B, and the date code is 0796.
  • OSR 2.1
    This update had only minor changes. The most important to technicians is the inclusion of USB drivers on the CD. Note that these drivers are not a part of the operating system, and thus are not loaded automatically. The USB drivers require the PIIX 4 drivers to be loaded (which are shipped on a separate floppy called "Intel support diskette"). Installing the USB drivers overwrites certain PIIX 4 files, however, so the PIIX 4 drivers must be loaded a second time. In order for a Windows 95 system with USB support to be fully functional. The version number of OSR 2.1 is also 4.00.950 B, but the date code is 0197.

There are four versions of Windows 98 you will see: Win98 standard, Win98 upgrade, Win98 Second Edition, and Win98 Step-up.

    Dell first started shipping Windows 98 on June 15th, 1998. Though Windows 98 became available on this date, we still offered Windows 95 OSR2.1 until August 25th on Dimension systems. Some home users and many small businesses still requested the older operating system for compatibility reasons. If a customer has this version of 98, it will appear in DPS and DCSS.
    The version for Windows 98 (Standard) is 4.10.1998
    Even though Windows 98 was not officially released until June 15th, there was a demand for this new product several months before its release.

    The version for Windows 98 (Upgrade) is 4.10.1998

    The Win98 Second Edition is an updated version of Windows 98, with many updates and bug fixes. Although MS considers 98 SE a "new" OS, it is essentially an update. The full install is referred to as Second Edition, there is an update though that is called the Step-up (which will be discussed shortly.) The biggest differences we will be concerned with between Win98 and Win98 SE are:
    1. IE 5.01
      The integrated version of Internet Explorer for SE is 5.01
      ICS is essentially a proxy server that allows multiple systems on a home network to connect to the Internet using the single connection from one computer. ICS can use modems or network cards.

    The Step-up is an update to Windows 98 that will bring it up to Windows 98 Second Edition.


The following is a chart displaying the areas in which DOS, Windows 3X and Windows 9X differ.

Windows 3X
Windows 9X
GUI No GUI unless through shell program (DOSshell) GUI, but needed DOS to boot GUI is fully integrated with DOS, not a separate copy.
Code 8 or 16-bit code. 16-bit code 32-bit code for device drivers and programs. Support for 16-bit Windows 3.1x applications for backward compatibility
File System Only supports FAT16 and FAT12. Uses DOS file system (FAT16 or FAT12) Support for FAT12, FAT16 and FAT32 (with OSR2 and up).
Plug-n-Play No PnP support. No PnP support. Support for PnP.
Tools No built in system tools or utilities. Windows 95 has few built-in system tools and configuration utilities. Windows 98 has many tools that can be utilized for troubleshooting and configuration.
Overhead Much smaller overhead since command prompt only and smaller system requirements. GUI requires lots of system resources (HD space and RAM) to maintain Much larger overhead; requires more hard drive space and higher system requirements.
Multi-tasking Single tasking Cooperative Multi-tasking Cooperative for 16-bit Win3.1x apps. Pre-emptive multi-tasking for improved performance with 32-bit apps. Background processes have been improved.
Mouse Support only for single mouse button. Support for two-button mice Support for two-button mice.

Windows 9X Architecture

Virtual Machines handle different types of applications in different ways.

    DOS applications run in separate memory and each runs within its own VM.
    One failing DOS app won't affect others.
    With each program getting its own VM, uses LOTS of memory & resources.
    DOS apps cannot truly share info.
  • WIN16 APPS
    Win16 applications run together in shared memory within the same VM.
    With all apps running in shared memory, uses fewer resources.
    Win16 apps can share directly.
    One failing Win16 app crashes them all.
  • WIN32 APPS
    Win32 apps run in separate memory (without need for VM).
    Run in separate memory but can still share.
    One failing Win32 app won't crash others.
    None (Except the price to upgrade to Win32 version.)

    This is a dynamic region on the HDD handled best by Windows 95. The region serves best if it is contiguous, therefore it is a good idea to Defragment the HDD occasionally. Problems can occur if a user makes changes to this size and management of this region.
    Note: This is found under the Performance tab in "System Properties"

    A quick overview of multitasking and threads.
    '98 will feed the most hungry, but not ignore the least.
    Priority boosting; How '98 feeds the hungriest (the loudest priority)