Today, you can’t buy a new x86 processor clocked at less than 1GHz – most desktop processors have base clocks well above 2GHz, faster than 3GHz. However, in the 1980s, processors ran at just a few MHz – the IBM PC ran at just 4.77 MHz.
Is it possible to run modern Windows on a processor with this frequency? Developer and popular YouTuber NTDEV proved that it is possible: he was able to download and run Windows 7, released in 2009, on a Pentium-S processor that was clocked down to 5 MHz – 995 MHz below the minimum system requirements. The test system also had 128MB of RAM installed, which is far less than Windows 7’s minimum requirement of 1GB.
In a YouTube video, NTDEV demonstrates the system, which is a virtual machine running in the 86Box emulator. The demo shows booting into Windows 7 Ultimate, running the WCPUID program showing the 5.00 MHz frequency, and even running Notepad. The timer in the video is sped up, but it shows that it took more than 28 minutes for the Windows 7 desktop to appear!
Course
EXCEL FOR BUSINESS
Master Excel in just 1.5 months and increase the efficiency of business processes in your company.
REGISTER!
A choice of normal and safe mode is available at boot. NTDEV chooses normal, but it actually boots into safe – the process shows all .sys, .dll, and .exe files as they boot. The enthusiast told Tom’s Hardware that he edited the boot configuration so that even selecting normal mode booted into safe mode.
To get Windows 7 to boot and run on such a slow CPU, NTDEV disabled a ton of drivers and services – only three services are running on the system. It was also necessary to bypass the authorization system.
At a frequency below 50 MHz, the logonUI screen does not want to load. So to get access to the command prompt I had to put the OS into a pseudo-OOBE state by modifying the registry and deleting everything in the c:\windows\system32\oobe folder so it wouldn’t boot.
OOBE is a mode that is enabled when the Windows installer starts. There is no Start menu or Windows Explorer, but the Command Prompt is available by pressing Shift + F10.
The NTDEV desktop shown in the video is devoid of the Start menu, wallpapers, and the windows are launched in the simplest design. In order to run the WCPUID/Real Time Clock Checker program, it was necessary to enter the path to it in the command line. “Notepad” was also launched.
At one point in the video, NTDEV was able to run four different programs: Command Prompt, WCPUID, Winver (showing the Windows 7 version), and Notepad with typed text – resulting in a very limited but fairly stable working environment.
The enthusiast said that he was actually running Windows 7 and with a clock frequency of only 3 MHz, but its functionality was not enough to create an interesting video. Also ran Windows 7 with only 36MB of RAM, but chose 128MB so the test system didn’t need a page file. In reality, the system used only about 70 MB during the demo.
The virtual machine also uses much less storage space than the 16 GB specified in the Windows 7 system requirements. It uses less than 1 GB to host data, and a disk image with a .wim file for the OS takes up less than 350 MB.
NTDEV is not stopping there and is looking for ways to make Windows 10 or Windows 11 work on a processor with a clock frequency of less than 1 GHz. He’s already managed to get Windows XP running at just 1 MHz: This thing took 3 hours to boot!.
An enthusiast has created a simple emulator that runs Windows 95 on almost any platform
