[Info-vax] Assistance needed!! working RM05 drive and VAX needed for proje

[Johnny Billquist]

On 2023-09-28 18:41, Dave McGuire wrote:
> On 9/28/23 06:55, Johnny Billquist wrote:
>>>    Or indeed any Unibus PDP-11.  Or any Qbus PDP-11 running directly 
>>> to SMD
>>> with an SMD controller that's format-compatible, which many are.
>>
>> Nope. The RM05 supposedly will not work on the RH11. Too slow for the 
>> disk. RH11 only supported RM02, RP04, RP05 and RP06.
> 
>    Ahh, I did not know that.  Will it actually fail to work, or just not 
> work very well (overruns/retries)?  The distinction matters a lot when 
> the object is to recover old data from media that nobody else can handle.

I've never actually tried running en RM05 on an RH11. I've not tried an 
RP07 either. But I suspect you might be dropping data on the DMA 
transfer, so potentually a non-solvable overrun problem.

I know that I had problems with the RP07 on an RH70. However, tne RP07 
can be set in an interleave mode that drops the transfer rate some, 
which is enough for the RH70 to keep up.

>> As for SMD - not sure. DEC certainly used those OEM drives, but for 
>> some reason the capacity was always less than the original drive, 
>> which makes me wonder if DEC did something more funny as well.
> 
>    We'll check the print sets when/if someone takes on that project. But 
> my admittedly decades old memory does recall that a CDC 9766 on an 
> Emulex controller (possibly an SC03) is media compatible with an RM05.

That would be interesting to get confirmed.

>    It's definitely the case that an Emulex controller (specifically) for 
> the VAX-11/750, whose model number I've forgotten, connected to a CDC 
> 9762 is media-compatible with the RM02.  I ran such a configuration at 
> work in the early 1990s and regularly moved packs between the two.

That's interesting, and good to know. The RM02 and RM03 are the same 
drive, and packs can be moved freely between them. The RM02 just spins 
slower.

   Johnny