Memfill : Fills the Available Memory for Testing

The one problem that we often face when running an older application on a newer system is that the older application fails to work with faster processors (CPU) and larger cache. The applications created in the times of Windows 95 were designed to run on computers with very little cache like 1 MB which was a big deal on those times. When they are run on modern computers with huge amount of memory, some of them simply fail to allocate enough memory ending in serious errors. This usually happens because of the way memory addresses are handles in those older applications.

Memfill is an application that addresses this issue and can offer some respite. Memfill, as the name of the application suggests, fills the system memory with random data. When the memory is full, the available memory is only a tiny portion of the total memory. This tricks the older applications to believe that the total available memory on a modern system is just a small amount. For example, if you have a total 16 GB of memory, you can fill 13.5 GB of memory using Memfill which leaves just enough memory for the operating system to run and leave only a few hundred megabytes for the older applications.


Memfill is a portable application and comes in a ZIP archive. Inside the ZIP archive are both a 32-bit and 64-bit application. We can run any of them but 64-bit version offers better compatibility with modern computers. It uses some SSE instructions like MOVNTQ to fill the memory.

After launching Memfill, we can set the amount of memory to be filled and then click on the Fill button. It will then show the progress bar and the time taken to fill that much memory. Later, you can click on the Free button to release all the memory. Because of the information displayed, we can use it to benchmark the cache speed of the processors too.

You can download Memfill from