1964: control store
The control store of the IBM 360
On display is the control store of the IBM 360 mainframe architecture from 1964. It is considered as the first architecture, which covered the entire range of scientific and commercial applications. Supported programming languages were e.g. the assembler language, Fortran and Cobol.
It is a capacitive read-only memory read through a induction coil. The word length is 60 bits. The micro instructions are wired on a Mylar strip. 8-bit addressing, binary, decimal and floating point operations were possible. Subsequent optimization of the microcode was not provided in this model due to the hard wiring, however, possible in other models. The reading was processor dependent, with a cycle time of 60 to 900 nanoseconds.
The introduction of the control store was an important factor for the success of computer architecture. Because of the possibility to install micro programs, it was even possible to run programs written for older IBM systems (often faster). Software was stored on punch cards and magnetic tapes.
