DSSI support for NetBSD: request for docs.

From: Johnny Billquist <bqt_at_update.uu.se>
Date: Wed Feb 27 08:51:37 2002

On Wed, 27 Feb 2002, Gunther Schadow wrote:

> > Johnny Billquist wrote:
> >>:-) I have a bunch of UDA50, both for my PDP-11s, and for the 8650.
>
> Johnny, were you suggesting you have a *spare* one among them?

If someone have a PEP-70/HC-70 kit to trade with, yes.

> If I'm not mistaken the whole idea stems from BSD anyway (just as
> the whole Ultrix does.) In 386/BSD and early FreeBSD the config(8)
> syntax distinguished controller from device.

That's a different issue. The idea DEC had with MSCP is that you separate
the disk controlling from actually transporting the commands to the
disk. So you actually have a two-layer controller.

BSD did not have that at the 4.3 era.

> Here this is from
> GENERIC.allvax of 4.3 BSD:
>
> controller mba0 at nexus ?
> controller mba1 at nexus ?
> ...
> disk hp0 at mba? drive 0
> disk hp1 at mba? drive ?

Note that you don't any concept of the abstract disk for massbus. Instead
massbus disks are massbus disks. There is no abstract layer even in
hardware. You directly access the different control and status registers.

> controller uba0 at nexus ?
> controller uba1 at nexus ?
> ...
> controller uda0 at uba? csr 0172150 vector udaintr
> disk ra0 at uda0 drive 0
> disk ra1 at uda0 drive 1
> ...
>
> controller bi0 at nexus ?
> controller kdb0 at bi0 csr 0 vector kdbintr
> disk kra0 at kdb0 drive 0
> disk kra1 at kdb0 drive 1
> disk kra2 at kdb0 drive 2
> disk kra3 at kdb0 drive 3
>
> So, just want the record to be straight, the beautiful design most
> probably comes from Berkeley. I do admit though that they don't
> seem to have a separate mscp controller, which I though Ultrix had,
> but again, I should be looking before talking ...

No, you noted correctly. BSD don't have a separate mscp
controller. Instead they have a different driver for each hardware
controller, which also means that you have ra for disks attached to
UDA50/KDA50 while you have kra for disks attached to KDB50.
Yet they are all MSCP controllers, talking the same language. However,
there are some differences on how you actually talk to a KDB50 compared
to a UDA50.
They sit on totally different buses...

        Johnny

Johnny Billquist || "I'm on a bus
                                  || on a psychedelic trip
email: bqt_at_update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
Received on Wed Feb 27 2002 - 08:51:37 GMT