[Info-vax] booting vaxstation off alpha

[Stephen Hoffman]

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.  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.


-- 
Pure Personal Opinion | HoffmanLabs LLC