OEM Downgrade to Windows 7 Pro in a Virtual Machine

Tutorial Video


This guide will instruct in creating a Windows 7 Virtual Machine using VMware Workstation Player. We will use a Dell OptiPlex 7050 as an example, this model has a 7th Generation Processor and a windows 10 Pro License. The 7th Generation Intel Processor has no driver support for Windows 7 so we must use a Virtual Machine. We will pass through the SLIC 2.1 from the OptiPlex 7050 to the Virtual Machine for Product Activation.

Download Links

VMware Player

Windows 7 ISO

See my guide for downloading a Windows 7 ISO if you don't have one:

OEM Cert Collection

If you are using a system with an OEM License (including OEM Downgrade Rights from Windows 8.x Pro and Windows 10 Pro) on a computer manufacturered by a major OEM such as Dell, HP, Lenovo, ASUS, Acer, Compaq, Gateway, Packard, Fujitsu, IBM, MSI, Samsung, Sony or Toshiba you are best to install Windows 7 without a Product Key and activate post installation using OEM System Locked Preinstallation – the same BIOS based Product Activation mechanism of factory settings. Doing so will save you from having to call Microsoft to activate by phone.

SLIC Passthrough Code for a VMware Virtual Machine Configuration File

This will only for systems with Windows 8.1 Pro OEM and Windows 10 Pro OEM Licenses. It will not for systems which have a Windows 8.1 Home OEM License or Windows 10 Home OEM License. These systems have the following stickers:

It will also not work for a Windows 8.1 Retail License or Windows 10 Retail License of any Edition.

Add the following to your VMware configuration file.

firmware = "efi"
acpi.passthru.slic = "TRUE"
acpi.passthru.slicvendor = "TRUE"
SMBIOS.reflecthost = "TRUE"

Do not add the first line for Windows 7 32 Bit. For 64 Bit add the first line but check for the line:

firmware = "bios"

If it exists delete it. This will prevent you from booting to BIOS instead of EFI. Note you will not be able to Boot with EFI if your install.wim on your ISO is greater than 4 GB for instance if you have slipstreamed drivers and updates to the install.wim.


Many people use VMware to just run legacy software, others may need to run legacy software to connect to legacy hardware such as an older scientific instrument. Make sure you have the required adaptors:

If your computer is brand new and only has USB Type-C connectors then you may need a USB Type C to USB adaptor to interface to legacy hardware. VMware player can readily connect to legacy devices over USB.

For Serial Ports I’ve found the following by plugable to be the most useful and have tested them on several legacy scientific instruments in the lab.

If your software is on a CD/DVD or Floppy Disc, you may however have an issue because the host PC you wish to virtualise your VM on does not have a CD/DVD drive. Firstly if you have an old computer with a CD/DVD drive then you should use WinImage to convert your CD or ImgBurn for a DVD to an ISO which can subsequently be loaded as a Virtual Drive in the VM. For more details see WinImage and Connecting to Legacy Hardware or ImgBurn. You can also buy USB CD/DVD Drives and USB Floppy Drives.

Installing VMware Player

Launch the setup.exe and accept the User Account Control:

The setup will begin:

Select Next:

Accept the License Agreement and select Next:

Select Next:

Select Next:

Select Next

Select Install:

Select Finish:

Configuring a Windows 7 Virtual Machine

Launch VMware Workstation Player:

Select use VMware Player for non-commercial use or alternatively purchase a license and input the product key:

Select Finish:

Select Player:

Select New → Virtual Machine:

Select I will install the Operation System Later.
(Selecting the second option to Load a ISO will begin an auto-install and this will not give the language or regional settings, defaulting to US English)

Select Microsoft Windows and Windows 7 64 Bit:

Use the default location or change drive. In my case I will install to my secondary SSD:

Select Next:

Select Customise Hardware:

The default memory should be 2 GB. If you have 16 GB of RAM change it to 4 GB:

If you have an i5 or i7 (7th generation or later) change the number of cores to 2:

Now load your installation ISO (the Dell Windows 7 Professional Skylake Reinstalaltion January 2016 ISO or Microsoft Windows 7 August 2016 Professional ISO is recommended as these are updated to include IE11 saving a bit of time when it comes to updating:

Select your Windows 7 ISO file and select Open:

Select Options:

Open the working directory in Windows Explorer:

Look for the Virtual Machine Configuration File:

Open in Notepad or Notepad++

Scroll to the end:

Copy the following code to the Virtual Machine Configuration File. Do not copy the first line for 32 Bit Windows 7 as it does not support EFI:

firmware = "efi"
acpi.passthru.slic = "TRUE"
acpi.passthru.slicvendor = "TRUE"
SMBIOS.reflecthost = "TRUE"

Close down Notepad or Notepad++ and Launch the Virtual Machine:

Installing Windows 7

The Windows 7 Installation will start:

You will get a dialogue box telling you that VMware wants to Download and Install VMware tools, you need these as system drivers for your Virtual Machine:

Windows will Load Files:

You'll see the Starting Windows Screen:

You can move the VMware Tools notification away:

Change your language settings as desired:

Select Install Now:

Accept the License Agreement and select Next:

Select Next:

Now wait for the installation to complete:

The install tools dialogue box will show after the tools are downloaded. Ignore this for now as Windows 7 needs to be installed before the system drivers (VMware Tools) are installed:

The VM will restart, your host PC will not though:

Enter your name and computer name and select Next:

Leave the Password Blank and select Next:

If asked for a Product Key (this Screen won't show if you used the Dell Windows 7 Professional Reinstallation ISO) Uncheck Automatically Activate Windows when I'm Online and select Next:

Select User Recommended Settings:

Set your Timezone and Press Next:

Select Home Network or work Network (if online):

Windows 7 will finalise your settings:

You will be taken to the Windows 7 Desktop.

Installing VMware Tools

Select Install Tools (if this does not show go to Player→Manage→Install VMware Tools)

Select Run Setup.exe

Select Yes:

Select Next:

Select Typical and then Next:

Select Install:

Select Finish:

Select yes to restart your VM:

Your VM will restart:

You now have system drivers installed meaning you can reshape the window of your VM and the display of the VM will automatically adjust and you can drag and drop from your host to your VM.

Checking Product Activation

Right Click Computer:

Select Properties:

Check if your Windows 7 is Activated:

It should automatically be activated if you used a Dell System (with a Windows 8.x Pro/Windows 10 Pro OEM License) and a Dell Windows 7 Professional Reinstallation ISO. The Product ID will contain OEM-899 meaning OEM System Locked Preinstallation is Applied.

If using the Microsoft ISO you and a system with a Windows 8.x Pro/Windows 10 Pro OEM License you will need to apply OEM SLP activation. Extract the OEM SLP files:

Select your OEM, in this case Dell:

Select your Edition, in this case Professional:

You will see an OEM folder:

Copy it:

Go to Computer and then to the C: Drive

Paste the OEM Folder:

Open the OEM folder:

You will have a slp.bat file:

Right click the slp.bat file and select Run As Administrator:

Select Yes at the User Account Control:

It will install the certificate, select OK:

It will input the OEM SLP key:

Select OK:

Press the spacebar to close the Command Window:

Now go to Computer:

Right click it and select Properties:

Windows 7 should be activated with a Product ID containing OEM-899

Product Activation Issues

The host PC must have a Windows 10 Pro OEM License or Windows 8.1 Pro OEM License. If it does it will have a SLIC Version 2.1. This can be checked using RWEverything. Install RWEverything and select Access → ACPI Tables. If you do not have a SLIC tab then your hardware is ineligible for this activation mechanism and you must use a Retail Key to Activate:

Next this SLIC 2.1 needs to be passed through to the VM. Launch RWEverything in the VM, if the host PC has one and the guest doesn't you will need to recheck your VM Configuration file to ensure that you have passed through the SLIC correctly:

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