Unix or BSD for Dec PDP 11/34 and 11/45

Paul Koning paulkoning at comcast.net
Fri Sep 17 19:59:31 CDT 2021

> On Sep 17, 2021, at 8:48 PM, Fritz Mueller via cctalk <cctalk at classiccmp.org> wrote:
> A fully-populated 18-bit address space on the /34 and /45 is only 128K words, which seems like a pretty tight fit for a TCP stack with practically sized buffers?
> I had always sorta assumed DELUA/DEUNA were only practically useful for TCP on extended Unibus machines (/70, /44, /24, etc.) but I could certainly be wrong on that assumption!
> 	--FritzM.

Certainly the 22 bit machines are a nicer choice, but various operating systems supported DECnet on 18 bit machines, which is a similar size problem.

As for buffers, one data point is that the DECNA -- the Pro (CT bus) Ethernet adapter -- has on-board buffer memory.  That memory is fixed at 64 kwords.  And compared to typical buffer allocations in DECnet (for RSTS anyway, the one I know) that's plenty large enough.


More information about the cctalk mailing list