[HECnet] LSSM group visit today

[Dave McGuire]

On 11/16/21 1:05 PM, Johnny Billquist wrote:
>>    Speaking of ddb, does it do a DTR query across the network to 
>> access the data?  Or something else?
> 
> Yes it does.
> Sources are on MIM. See
> MIM::HECNET:DDB.C
> and
> MIM::HECNET:DDBDTR.CMD
> 
> (Yes, DDB itself is written in C.)

   Very nice, I will look at it.  I've been wanting to learn Datatrieve 
programming.  Thanks for the source!

>>    It sounds like MAGICA is much bigger.  We don't yet have a Unibus 
>> expansion chassis connected to FANG, so we have limited Unibus slots. 
>> There's an RL02 and an RX02 in its rack, but no place for their 
>> controllers to live.
> 
> What? You only have the four slots in the CPU backplane? That's a rather 
> unusal and limited 11/70 setup.

   Yes, I removed the BA11-K expansion chassis when I got that system 
many years ago.  The system was going into my house, years before I ever 
knew I would be able to finally realize my dream of opening a big-iron 
museum, and the only thing in the expansion chassis was a DH11 and a few 
DZ11s, and that chassis was the only thing in that extra rack.  So, 
needing to reduce its size and power consumption for a home environment, 
I removed that chassis and rack from the configuration.  That was about 
twenty years ago.  The DL11-W, UDA50, and DELUA are currently the only 
Unibus peripherals on FANG.

   Now, with the machine at the museum with a lot more space and power, 
we're in the process of putting the expansion chassis back into the 
system, but with different contents.

> I think it was pretty much standard that you had at least one BA11 box 
> in any 11/70.

   Yes, I assume so; that's the only way I've ever seen them in the field.

>>    We also have an Emulex SC72 disk controller (actually a few of 
>> them), which is a board set that plugs into RH70 slots and implements 
>> an SMD interface.  We have a Fuji Eagle prepped and ready to go onto 
>> that, but we still need to cable it up, format it, etc.  I expect that 
>> to be much, much faster than the UDA50+RA73.  Hopefully we'll get to 
>> that sometime this winter.
> 
> That could potentially be much faster, yes.
> I haven't done any tests, but I suspect even some SCSI on the 11/70 and 
> some modern disk would be a big improvement. I think seek times on the 
> RA73 isn't that great.

   Before we got the RA73s, I was running an Emulex UC17 and a 200MB 
SCSI drive on that system.  I didn't do any tests either, but I think 
the bottleneck was the Unibus; the UDA50+RA73 doesn't really feel any 
different.

   That UC17 is now on my personal PDP-11/34 at home, connected to two 
Bernoulli 44MB drives.  I make disk images under simh, and dd(1) them to 
cartridges to run on it.  That 11/34 has no network interface, so it's 
not on HECnet, but I do run it occasionally, for soul-healing purposes. 
I may try to network it at some point.

> But the Unibus on the 11/70 is also known as possibly the slowest Unibus 
> around.

   Yes, that's why we'd like to move our mass storage away from that, if 
we can make it all work.

            -Dave

-- 
Dave McGuire, AK4HZ
New Kensington, PA