DESQView, from Quarterdeck, was a DOS application multi-tasker and in later versions functioned as an X client for applications on remote UNIX systems. It competed against IBM Topview. The original DESQ was just a task switcher, but subsequent versions offered preemptive multitasking of well behaved DOS programs on real-mode 8088 PCs. It gained popularity when DESQView 386 added virtual x86 support. This enabled the ability to multi task many poorly behaved programs, and was often used on BBSes due to its excellent COM port handling. It was later overtaken by OS/2 and Windows.