17 Sep
2021
17 Sep
'21
5:59 p.m.
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.
paul