MINIMOP provided an on-line, time-sharing environment (Multiple Online Programming, or MOP in ICL terminology), and typically ran alongside George 2 running batch jobs.
[1] MINIMOP was named to reflect its role as an alternative to the MOP facilities of George 3, which required a more powerful machine.
[2] MINIMOP would run on any 1900 series processor apart from the low-end 1901 and 1902 and required only 16K words of memory and two 4 or 8 million character magnetic disks.
All user I/O operations were trapped by MINIMOP and emulated rather than accessing real peripherals.
[3] The ICL Universities Sales Region started distributing MAXIMOP, and it was used at over 100 sites.