Arithmetic on the ELXSI System 6400

The ELXSI System 6400 is a new 64-bit general-purpose mainframe computer [1]. This paper decribes its arithmetic instruction set architecture and the organization of the arithmetic processor. The ELXSI instruction set supports a complete implementation of the proposed IEEE floating point standard [2], plus integer and decimal arithmetic. The System 6400 arithmetic processor uses ECL gate arrays to execute these instructions at high speed using a single board of hardware.