The SEDN program is the oldest program still in use ever
written by members of the ORD-GROUP;
its development started in 1981 before we even had disk
drives on the EXIDY. It was the editor of choice for the ORD-GROUP,
sorely missed on other systems.
The history of SEDN starts with the DJOE 'Pac-selector' rack for the
EXIDY computer. One of the Pac's in the rack was the so-called Development Pac,
which provided an assembler; another was the Word Processor Pac.
Unfortunately, the two Pac's were not compatible, leaving us with
an assembler without an editor. This motivated Luc to write a
assembler-compatible editor whose GUI was loosely based on the Word Processor Pac. The most outstanding feature of that GUI was that the current
line was always kept in the middle of the screen.
The initial version of this editor was called SRCED (SouRCe EDitor)
and was hand-assembled in memory; not having an assembler we had already become
very good at that. The five-character name is typical for the time
because the EXIDY cassette software did not support longer names.
At some point SRCED worked well enough; at that point a disassembly
was made which was laboriously commented and used as the base for
a new version written in assembly language, using the assembler.
A limitation of the Development Pac was that it had no linking loader,
hence the program had to be written as a single source file.
When the EXIDY got floppy drives in 1982, we eagerly dived into its CP/M 2.2
operating system. CP/M did not come with a good screen editor (we didn't
have WordStar at the time and wouldn't have liked it anyway), so we set out
to port the cassette-based SRCED editor to CP/M. We quickly modified the editor
to run as a CP/M program and renamed it SED (Sourse EDitor), dropping the 5-letter name. However, SED did not yet support loading and
saving files from disk, which we now needed to add.
To get started, we wrote programs LOS and SAS (LOad Source and
SAve Source) that
could load and save the edit buffer of SED from/to a CP/M file. This allowed us to continue using the existing SED while we wrote a disk-based version,
appropriately called SEDN, the N standing for New. Luckily,
the EXIDY CP/M software came with a real assembler and linking loader
(called EXASM and EXLINK, respectively) and it was now possible to
split programs over multiple source files (at first using assembler
INCLUDE statements, later using the infamous assembler statements
GLOBAL, INT and EXT; the latter two adding assembler error checking).
When the ORDINATOR came along, we naturally wanted to port SEDN to it
and we designed the video display hardware so that it supported
an EXIDY-compatible mode. The port
thus went very smoothly; the mode-switching code for the
video hardware was simply added to SEDN.
The TS system supplies system calls for mode-switching and setting
the cursor, thus obviating the need for direct hardware manipulation;
code to use these calls instead was of course easily added to SEDN.
SEDN was eventually renamed E (Editor) to save on typing;
it has seen continuous use on both the EXIDY and the ORDINATOR,
never really caving in even to WordStar.
SEDN is also mentioned on page 54 of the book "THE ORDINATOR PROJECT".