[TUHS] core

Johnny Billquist bqt at update.uu.se
Thu Jun 21 07:35:09 AEST 2018

On 2018-06-20 18:55, Paul Winalski wrote:
> On 6/16/18, Johnny Billquist <bqt at update.uu.se> wrote:
>> After Unibus (if we skip Q-bus) you had SBI, which was also used both
>> for controllers (well, mostly bus adaptors) and memory, for the
>> VAX-11/780. However, evaluation of where the bottleneck was on that
>> machine led to the memory being moved away from SBI for the VAX-86x0
>> machines. SBI never was used much for any direct controllers, but
>> instead you had Unibus adapters, so here the Unibus was used as a pure
>> I/O bus.
> You forgot the Massbus--commonly used for disk I/O.

I didn't try for pure I/O buses. But yes, the Massbus certainly also 

> SBI on the 11/780 connected the CPU (CPUs, for the 11/782), memory
> controller, Unibus controllers, Massbus controllers, and CI
> controller.


> CI (computer interconnect) was the communications medium for
> VAXclusters (including the HSC50 intelligent disk controller).

But CI I wouldn't even call a bus.

> DEC later introduced another interconnect system called BI, intended
> to replace Unibus and Massbus.

I think that is where my comment started.


Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

More information about the TUHS mailing list