The implementation of APL\360

Abstract

APL\360 is an experimental, conversational System/360 implementation of APL, the Iverson language. It provides fast response and efficient execution to a large number of typewriter terminals. With 40 to 50 terminals connected and in normal use, each with a block of storage (called a workspace) allocated, reaction time (defined as the time from completion of an input message until the user's program begins execution) is typically 0.2 to 0.5 second. At the terminal this is manifested by nearly instantaneous response to a trivial request. Under these conditions, the CPU is executing user programs about 75% of the time, while supervisor overhead and I/O waiting time amount to less than 5%. The APL processor is interpretive; however, because of the efficiencies afforded by array operations, program execution is often one-tenth to one-fifth as fast as compiled code. APL\360 is currently running on a System/360 Model 50 with 262,144 bytes of core storage, a 2314 Direct Access Storage Facility, and two 2702 Transmission Control Units to which IBM 1050 and 2741 Communication Terminals are connected via telephone lines.