ImDisk Virtual Disk Driver is a disk image emulator created by Olof Lagerkvist. It is free and open-source software, and is available in 32- and 64-bit variants. It is digitally signed, which makes it compatible with 64-bit versions of Microsoft Windows without having to be run in Test mode. The 64-bit version has no practical limit to the size of RAM disk that may be created. ImDisk Toolkit is a third-party, free and open-source software that embeds the ImDisk Virtual Disk Driver and adds several features. ERAM is an open source driver that supports making a drive that is up to 4 GB of the total amount of RAM, uses paged/non-paged memory and supports backing up the drive to an image. It works on Windows XP/NT/2000/7/10 (32 and 64-bit). Its driver and source code can be found by going to https://github.com/Zero3K/ERAM. AMD Radeon RAMDisk is available in free versions (RAM drive up to 4 GB, or 6 GB with AMD memory), and commercial versions for drives up to 64 GB. The free version is 'advertising supported'. Creates only a single drive (does not support multiple RAM drives). Can be backed up periodically to hard drive, and automatically loaded when the computer is started. AMD Radeon RAMDisk is a rebranded version of Dataram RAMDisk. Dataram's RAMDisk is freeware (up to 1 GB (reduced from 4 to 1GB - per October 2015 site visit) disk size) and was originally developed and marketed by John Lajoie through his private consulting company until 2001, when he sold his rights to Cenatek, before being acquired by Dataram. RAM disks larger than 4 GB require registration and a USD $18.99 single-user license. When purchasing physical RAM from Dataram, the RAMDisk license is provided free of charge. (Per DATARAM Government Sales on 4/25/2014, this is no longer the case.) Compatible with all 32-bit and 64-bit versions of Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, Windows Server 2008, and Windows Server 2003. A RAMdisk built specifically for gamers which features real-time file-synchronization, Steam integration, "USB3 Turbo Mode". The interface was designed to support both technical and non-technical game enthusiasts. Cost is $29 at Dimmdrive.com and $30 on Steam. ($14.99 on Steam as of 2018)   Can use Physical Address Extension to create a virtual disk in memory normally inaccessible to 32-bit versions of Microsoft Windows (both memory above the 4 GB point, and memory in the PCI hole).