Emerson MVME147 User Manual

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GENERAL INFORMATION
Introduction
The MVME147 MPU VMEmodule contains a port to the Small Computer 
Systems Interface (SCSI) bus.  The hardware interface is the WD33C93 SCSI 
interface controller.  
To relieve you of having to follow SCSI bus protocol, the SCSI firmware allows 
you to pass commands to the bus through high level command packets.  
Standard command packets are furnished, as well as custom SCSI sequence 
packets that you may easily modify to fit particular applications.  With this 
method, the firmware interface can greatly speed up your software 
development cycle.  
The SCSI firmware resides in two 128K x 8 EPROMs and is co-resident with 
MVME147Bug, the debug monitor for the MVME147 MPU VMEmodule.  
Features
The SCSI firmware offers the following features: 
Custom SCSI sequence packets that allow creation of customized 
functions 
TARGET role 
Multitasking -- up to 64 concurrent peripheral devices 
High level support of SCSI devices 
Interrupt mode allows real-time applications 
Polled mode -- non-interrupt operation 
DMA with memory/scatter/gather 
Multiple-user interface allows concurrent operation through independent 
drivers 
Six entry points 
Thirty-one "canned" or standard function packets 
Modes of Operation
When using the SCSI firmware, you have a choice of two modes of operation: 
Interrupt mode and polled mode.