RISC OS 3
full spelling ： Reduced Instruction Set Computer Operating System 3
Reduced Instruction Set Computer Operating System 3 or RISC OS 3 was the successor to RISC OS 2. It was first released as RISC OS 3.00 in 1991. RISC OS 3.0 was released with the A5000 computers.
RISC OS 3 was an upgrade from RISC OS 2. It is almost four times the size of RISC OS 2 and runs from a 2 MiB ROM. It improves multitasking and also places some of the more popular base applications in the ROM. Upgraded RISC OS 3.1 was released later and sold built-in to the A3010, A3020, A4000, A4 and later A5000 models. RISC OS 3.50 was released in 1994. In 1995 RISC OS 3.60 was followed and RISC OS 3.70 was released in 1996.