Before OS/360, IBM developed separate hardware and software for each computer model. Programs written for one system wouldn’t run on another.
Microkernel-like, with heavy reliance on a virtual machine Portable virtual machine: Dis VM runs the Limbo language everywhere
MULTI IDE showing INTEGRITY tasks, trace debugging & memory partitions
Minimalistic system — by design has a tiny attack surface Lacks multi-user accounts or advanced permissions
Technically not a standalone OS kernel, but a network operating system layer installed on top of MS-DOS or Windows
Monolithic with distributed system extensions
Beautiful Aqua GUI with advanced graphics (Quartz, Metal)
MenuetOS (also known as MeOS) Tiny footprint: Core OS fits on a 1.44 MB floppy (still with GUI, network, and apps)
MINIX is a historically significant OS that proved the practicality of the microkernel design and served as the catalyst for the world's most popular kernel, Linux
Multiplexed Information and Computing Service
Novell NetWare Monolithic, multitasking real-mode (in early versions), later protected mode
Plan 9 from Bell Labs
