[Info-vax] booting vaxstation off alpha

[Bill Gunshannon]

In article <kfdmid$5n5$1 at dont-email.me>,
	Stephen Hoffman <seaohveh at hoffmanlabs.invalid> writes:
> On 2013-02-12 07:48:22 +0000, Hans Vlems said:
> 
>> On 12 feb, 01:31, Johnny Billquist <b... at softjar.se> wrote:
>>> On 2013-02-11 13:44, Stephen Hoffman wrote:
>>> 
>>> 
>>> 
>>> 
>>> 
>>>> On 2013-02-11 07:54:11 +0000, Hans Vlems said:
>>> 
>>>>> DECnet over DSSI works fine, provided you get the incantations right.
>>>>> All I tried was CTERM and FAL and both worked as expected (reliable
>>>>> albeit slow).
>>>>> Another example of an undocumented, unsupported feature that works
>>>>> alright.
>>> 
>>>> Not that there is even a remote chance of seeing DSSI gear around, nor
>>>> any likelihood of IP over FC nor connections, but...
>>> 
>>>> If you ran any tests[1] with that, how well does that "albeit slow"
>>>> connection perform as compared with slow Ethernet?  CI wasn't known for
>>>> its network performance, as compared with DECnet over even then-current
>>>> 10 Mb Ethernet, and usual recommendations back then had CI at higher
>>>> cost as a backup connection.  I can't see DSSI being much better in that
>>>> regard.
>>> 
>>> That sounds weird. Do you know why?
> 
> Read up on the (complexity) of the CI controller, and decide for 
> yourself <http://lazowska.cs.washington.edu/p130-kronenberg.pdf>
> 
>>> I mean, CI was after all two redundant full duplex 70 Mbit/s channels,
>>> compared to the half-duplex 10Mbit/s ethernet. Not to mention the fact
>>> that the MTU of CI is much larger.
> 
> 70 Mb dual-channel, not duplex.
> 
>> Yes, I know what you mean Johnny. I don't think the CI was full duplex though.
> 
> Correct.  Some later-vintage CI controllers could use both channels in 
> parallel.
> 
>> But it clocked a lot faster than ethernet. The cables BTW were
>> physically remarkably similar,
>> other than the colour. Won't say much for the electrical
>> characteristics of the two of course.
> 
> CI cable was lower-loss than was fat-wire Ethernet. 

A wet clothesline was lower-loss than fat-wire Ethernet.  I know
it said RG8 on the cable, but it had to be the lowest quality RG8
manufactured.  I'm a ham and I threw all my old yellow cable in
the trash.

>                                                        I know a few 
> amateur radio operators were happy to have old CI cables, when CI 
> clusters were decommissioned.  Made great feed wire.  Assuming the 
> deinstallers didn't damage the coax cable in the process of removing it.

I wasn't aware it was 50 ohm.  I thought more like 72 ohm.  Wish I had
known that before I gave all mine away.

 
bill 

-- 
Bill Gunshannon          |  de-moc-ra-cy (di mok' ra see) n.  Three wolves
billg999 at cs.scranton.edu |  and a sheep voting on what's for dinner.
University of Scranton   |
Scranton, Pennsylvania   |         #include <std.disclaimer.h>