Path: utzoo!attcan!uunet!cs.utexas.edu!usc!apple!portal!cup.portal.com!Chuck_SirVAX_Staatse
From: Chuck_SirVAX_Staatse@cup.portal.com
Newsgroups: comp.sys.dec
Subject: ADDing new SCSI device
Message-ID: <30706@cup.portal.com>
Date: 12 Jun 90 17:15:22 GMT
Organization: The Portal System (TM)
Lines: 18

I am considering making a Widget that would interface to the SCSI bus.
This device would do block mode transfers (like a disk) when accessed
thru one device address, and character like transfers when accessed 
at a different device address. Although designing  the hardware
play on the SCSI bus seems very straightforward, getting a user written
program to access this device thru a standard SCSI port is not
so straightforward.  My user program should be able to:

           dma_read(staring_block,buffer_address,byte_count,&stat)
           dma_write(staring_block,buffer_address,byte_count,&stat)
           char_read(buffer_address,byte_count,&stat)
           char_write(buffer_address,byte_count,&stat)

In addition, each call should be able to set up a function address, so
that the specified function could be called when the operation is
finished.

Is this functionality available without writing a device driver?