IBM SYSTEM/360

IBM-System-360

The IBM System/360 mainframe was announced on April 7, 1964 by IBM.  This machine was the first to adopt the 32-bit word design which made more sense for arithmetic calculations. IBM invested over $5 billion to develop the System/360 machine. IBM estimated the machine would cost $1 billion to bring to market.

The System/360 replaces all of the older model machines and it supports backwards compatibility using emulation. The machine had to be reset when the emulator was enabled or disabled. The machine was the first to use microcode for the CPU instruction set.

The CPU could handle register to register, and register to memory transfers. This make it possible to have complex programs that were memory mapped for better overall performance. The instruction set is rich with functions to make it easier implement FORTRAN.

Memory ranged from 4KB to 64KB depending on the options. Memory is an expensive option which few could afford in 1964.

The new Solid Logic Technology in 1964 that meant a faster and a much smaller machine. Rival machines were not as sophisticated.

Tape was the standard storage unit and the new hard disk assemblies created a hybrid storage system.  Tape is removable so it could be used to archive data on storage racks until needed.

The System 360 is the first machine designed for corporate use and not exclusively for government and  universities.

The IBM System/360

Thomas J Watson Jr made a huge gamble with the System/360 and the commitment that IBM made to the platform ensured its success. The IBM 2401 tape system was instrumental in system peripherals. The tapes moved data back and forth to the mainframe to be able to handed vast amounts of data quickly. IBM was able to sell a lot of IBM 2401 tape systems which make the mainframe successful. The standard size of a byte was effectively set at eight bits with the System/360 and nine-track tape.

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