Path: utzoo!attcan!uunet!cbmvax!jesup
From: jesup@cbmvax.commodore.com (Randell Jesup)
Newsgroups: comp.periphs.scsi
Subject: Re: NEC CDR-35 portable CDROM drive
Message-ID: <12378@cbmvax.commodore.com>
Date: 7 Jun 90 03:35:50 GMT
References: <12215@shlump.nac.dec.com> <8575@goofy.Apple.COM>
Reply-To: jesup@cbmvax (Randell Jesup)
Organization: Commodore, West Chester, PA
Lines: 58

In article <8575@goofy.Apple.COM> Smyers.S@AppleLink.Apple.COM (Scott Smyers) writes:
>Hopefully this state of affairs will improve in the future.  The SCSI CAM 
>committee has formed to address this exact issue.  I was a member of that 
>committee for about the first 10 meetings and at every meeting someone 
>brings up a problem exactly like you're describing - "I already have a 
>SCSI bus on my PC - why can't I buy brand X SCSI device and plug it in?"  
>God and ANSI willing, some day, you will.

	We already have this on the Amiga.  We have a protocol called
"scsidirect" which allows you to pass a control structure to the device
driver, which will then send your command (and optionally retrieve any
sense information).  The structure used looks like this:

/*
**	(C) Copyright 1988 Commodore-Amiga, Inc.
**	    All Rights Reserved
*/
...
struct SCSICmd {
    UWORD  *scsi_Data;		/* word aligned data for SCSI Data Phase */
				/* (optional) data need not be byte aligned */
				/* (optional) data need not be bus accessable */
    ULONG   scsi_Length;	/* even length of Data area */
				/* (optional) data can have odd length */
				/* (optional) data length can be > 2**24 */
    ULONG   scsi_Actual;	/* actual Data used */
    UBYTE  *scsi_Command;	/* SCSI Command (same options as scsi_Data) */
    UWORD   scsi_CmdLength;	/* length of Command */
    UWORD   scsi_CmdActual;	/* actual Command used */
    UBYTE   scsi_Flags;		/* includes intended data direction */
    UBYTE   scsi_Status;	/* SCSI status of command */
    UBYTE  *scsi_SenseData;	/* sense data: filled if SCSIF_[OLD]AUTOSENSE */
				/* is set and scsi_Status has CHECK CONDITION */
				/* (bit 1) set */
    UWORD   scsi_SenseLength;	/* size of scsi_SenseData, also bytes to */
				/* request w/ SCSIF_AUTOSENSE, must be 4..255 */
    UWORD   scsi_SenseActual;	/* amount actually fetched (0 means no sense) */
};

	The scsi_Flags also specifies if you want automatic request sense,
as well as direction (read or write).

	Most of our 3rd-party scsi controller developers are now using this,
making things very nice.  Combined with a standard partitioning method, we
can take a drive from one 3rd party controller and plug it into a different
controller, and all the partitions will appear (or even boot off it).  You
can take standard archive programs that talk to scsi tape drives, and use them
on any controller, etc, etc.

	For hard drives, there are several programs for partitioning that
read/write the partitioning standard (RigidDiskBlock).  Most of these are
quite good at doing all the setup of a drive for you automatically, using
Inquiry, Read Capacity, etc via the scsidirect protocol.

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com  BIX: rjesup  
Common phrase heard at Amiga Devcon '89: "It's in there!"