[HECnet] Drives for a VAX-11/730

[Johnny Billquist]

On 2013-07-16 03:34, Bob Armstrong wrote:
lee.gleason at comcast.net wrote:
I remember poring over the drawings for the RB730 at the time,
wondering if a plain non-DEC SMD drive would have worked ....

    Yeah - I was wondering the same thing.   The RM80 Technical Manual doesn't seem to be online, but the RM MASSBUS Adapter Technical Manual

	http://bitsavers.trailing-edge.com/www.computer.museum.uq.edu.au/pdf/EK-RMADA-TD-001%20RM%20MASSBUS%20Adapter%20Technical%20Description%20Manual.pdf

has a lot of information about the RM80 too.   It looks like the RM80 used the same MASSBUS Drive Control Logic box as the RM0x drives.   As I remember, the RM02/3/5 were CDC 9760-something drives, which were SMD.   Of course it's possible that the DEC OEM versions had customized interfaces.

    The RB730 Technical Manual is also online

	http://bitsavers.trailing-edge.com/pdf/dec/vax/730/EK-RB730-TD-001_VAX-11_730_IDC_Technical_Description_Sep82.pdf

and it has a description of the R80 interface, but this version doesn't look that much like SMD to me.

While the Massbus adapter talked SMD for all these drives, the Massbus adapter for the RM02/03 is not the same as for the RM05. Unless I remember wrong, they are very different beasts. And they identify themself as the exact type of drive on the Massbus as well, and the capacities and geometries differs, which is important, as Massbus drives expose all these details to the computer.

So I very much doubt the Massbus adapter for the RM80 is the same as either of the others.
(The RM02 and RM03 is the same drive, just with different rotational speed.)

Also, the RP04/05/06 are also SMD drives inside, but with a totally different Massbus - SMD interface. And yes, as John mentioned, DEC actually did slightly change the SMD interface so that it is not a plug and play with any other SMD drives, even if other parameters would be compatible.

Oh, and by the way, I'm not sure the R80 is an SMD drive at all. Is it?

	Johnny