|Kernel:||Time shared exokernel|
|Task Model:||4-level round robin|
|Platform(s):||S/370, S/370-XA, S/390, zEC12, zBC12, z114, z196, z10, z9 (S390 and z/Arch families)|
|Language(s):||Assembly (GAS Syntax), C|
|License:||Unlicense (Public domain)|
UDOS is a small OS made for mainframes. It has an integrated console for executing commands and consists of the normal things an OS has: Memory management, VFS, Queued I/O commands, Disk drivers, Filesystem drivers, Text printing & Input processing. All of that but in the mainframe world.
It also supports the equivalent of SYSCALL, with it's own ABI.