Re: What's under development?

Dave Hudson <dave@humbug.demon.co.uk> writes:

> ...
> Has there been any discussion of how to handle devices under SCSI, such as
> how to keep the target specific code separated from the SCSI card specific
> code?
>

Dave,

I'm writing the SCSI driver for VSTa. I'm implementing the driver to
the CAM (Common Access Method) specification, so to answer your
question, we have had that discussion. Target specific code is handled
by a layer called the peripheral driver layer. Each type of device
(disk, tape, etc.) is handled by a different peripheral driver. SCSI
card specific code is handled by the SIM (SCSI Interface Module) layer.
In between the two layers is the XPT (transport) layer, which is
responsible for routing requests from the peripheral drivers down to
the appropriate SIM.

As far as status of the driver goes - a peripheral disk driver is
up and running, talking (via XPT calls) to a SIM driver for the
Adaptec 1542C (as far as I know, this should also work for the
154xB too). There are still a few things left to code before its
ready for prime time, including the breaking up of large I/O
transfers into smaller ones and various cleanup items.

Hope this helps.

                                        Mike Larson
                                        larz@world.std.com
Received on Thu Dec 16 09:58:17 1993