A General Purpose Fastbus Master (GPM) and Memory Module (DSM) for Online Applications

The GPM [1] is a high performance Fastbus master/ slave, driven by 68 000 (or optionally 68 020/68 881 processors). Developed for general purpose applications it will perform control, trigger and diagnostic functions in three different experiments [2] at CERN (DELPHI, L3. VIRTUS). Commercially available as single-board Fastbus master/ slave, the GPM is a cheap processor component which can be connected to the DSM Fastbus dual-slave memory [3] to perform as a low-level trigger processor, event formatter or data-spy. The GPM supports interprocessor interrupts via a Fastbus CSR register, interrupts on events in the Fastbus (like SR), and external interrupts. The GPM (fig. 1) Is equipped with 1/2 Mbyte of RAM, 1/4 Mbyte of ROM and a 32 Kbyte Fastbus I/O buffer. Any Fastbus operation can be generated as mixture of autonomous block transfers and assembly-language instructions which are directly executed in Fastbus. Powerful diagnostics can be performed by the possibility to address its own slave-port, via the Fastbus and the applicability of the debugging monitor commands to individual Fastbus/68 000 cycles. A terminal and host connection is available. The DMA supported parallel port can be used for interface applications. For external interrupts and coaxial pulse I/O, a NIM pulse interface is available. The 2 Mbyte Dual Slave Memory (DSM) can be used either as a stand-alone Fastbus memory, or as a memory extension module of a GPM, with independent I/O on crate and cable segments (fig. 2).