Announcing TCP/IP for RSX-11M-PLUS

Johnny Billquist bqt at
Thu Jan 15 07:29:27 CST 2015

On 2015-01-15 12:41, Lars Brinkhoff wrote:
> Johnny Billquist wrote:
>> Pontus Pihlgren wrote:
>>> Why would PDP-10 be so much harder?
>> Everything is of course doable, but there will be a whole lot of bit
>> fiddling and juggling doing TCP/IP on a PDP-10.
> If you just use the "natural" 8-bite byte packing for a word
> (i.e. what IBP does, and also the subset the one-word global byte
> pointers support), I don't see that it would be so much harder.  The
> PDP-10 byte instructions are quite convenient for bit fidding.

They are. But you also have to, sometimes, do calculations to create 
your byte pointers, as the byte you want to start looking at might not 
be at the beginning of a word. And the same is true for some 16- or 
32-bit quantities. And you need to do arithmetic on 16- and 32-bit with 
the correct byte ordering, which might mean you have to move bytes 
around, and truncate things.

The story goes on. Like I said, it is definitely doable, but it do 
require some fiddling. The devil is in the details. Once you actually 
start coding, you'll discover all the small annoyances.


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

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