The IBM System/360 Model 30 was a popular IBM mainframe announced in 1964 across the world as the least powerful of the System/360 range of four compatible computers – the first range in the world to allow programs to be written that could be used across a range of computers. The Model 30 had a maximum main storage of 64K bytes; its CPU used an 8-bit microarchitecture with only a few hardware registers; everything that the programmer saw was emulated by the microprogram. Programming was mostly in the COBOL and Assembler languages for the commercial applications that were the predominant uses of this computer. Many installations included the IBM 1401 compatibility feature.
The IBM operating system used was OS/360 or usually the realistically sized DOS/360.