OSF/1 Tru64 UNIX ECOFF Advanced Computing Environment Ultrix DECstation Armando Stettner List of Unix systems AT&T Computer Systems PA-RISC DEC 3000 AXP 64-bit computing Kendall Square Research Mach (kernel) DEC Alpha Comparison of Java virtual machines Memory management unit List of operating systems Comparison of BSD operating systems Santa Cruz Operation HP 9000 Linux malware Timeline of operating systems Digital Equipment Corporation OpenLisp Comparison of operating systems Comparison of operating system kernels