[Simh] Emacs-clone for RSX?

[Johnny Billquist]

On 2016-05-29 19:43, Phil Budne wrote:
> I don't recall it being great,
> but there was an emacs11 written in DEC TECO-11;
>
> ftp://ftp.ultimate.com/emacs/emacs11.urls
> ftp://ftp.ultimate.com/emacs/emacs11.tar.Z
>
> http://www.ibiblio.org/pub/academic/computer-science/history/pdp-11/teco/emacs11/aaareadme.txt
> says:
>
>     This directory contains Fred Fish's EMACS for TECO-11 v35 or higher.
>     Fred hasn't used this stuff since 1982.....
>
> 			    Pete Siemsen, 28-Jul-1989
>
> The code is well commented!

Yes, I know about it.
I actually did sortof an Emacs clone in TECO-8 many years ago. It's 
actually pretty easy to do a decent implementation in TECO. The problem 
is that you cannot really edit large files. TECO-8 and TECO-11 can edit 
arbitrarily large files, but only as a stream. You read in a page of the 
file (where a "page" is a bit loosely defined), you edit it, and then 
you pass it on to the output, and read in the next page. At that point, 
you cannot go back to a previous page anymore. And all editing is 
happening within the buffer that you have in memory. So all addressing 
is done local to the page you have in memory.

So, while cool, and somewhat fun, it have some rather severe limitations 
if you want to edit large files. And this is a TECO-11 limitation, and 
cannot really be solved in a good way by any code written inside 
TECO-11. What I did for my implementation for TECO-8 was that I keep a 
count of which page I was on, and if I wanted to go backwards, I had to 
close the file, reopen it, and read from the beginning until I was at 
the previous page, and then work from there.

	Johnny

-- 
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