A computer is not useful without an operating system. I wrote several
operating systems for the two computers I designed and built as a hobby.
These operating systems were extremely useful in their day. I no longer
use them for the same reason that people do not use MS-DOS any more.
Language: Z80 machine language
Size: 8 KBytes
Monitor 3 was a combination of machine language debugger, cassette tape
loader, as well as the first disk operating system. I used it for
machine language programming - entering Z80 opcodes directly into the
computer's memory, jumping to them, and hoping bad things did not happen.
That is PUSH DE, PUSH IY, and LD IY,2000 at location 0080
in case you have not memorized the Z80 opcodes.
Monitor 3 originated the floppy disk and file system formats that were
used by subsequent operating systems. These were not compatible with
any standard 8-inch diskette format.
Language: Z80 assembly language
Size: 3K lines
GDOS was a more-or-less conventional disk operating system. It ran
smaller programs such as disk utilities. Large programs such as BASIC
5.1 were effectively their own operating systems.
Language: 68000 assembly language
Size: 7K lines
EDIX was the last operating system that I developed. It was an
immensely useful program that spawned a large number of application
programs. EDIX featured a hierarchical file system and required a hard
disk drive. EDIX could read and write GDOS floppies.
Despite its name, EDIX was more similar in capabilities to MS-DOS than
UNIX. Later versions supported relocatable object code and cooperative
multitasking. EDIX was a single-user system with no protection between
tasks, or between tasks and operating system. EDIX was not portable to
The screen shot shows a 2004 build even though development ceased in
Language: E language
Size: 4K lines
Edwin was the windowing component of EDIX. Edwin sat on top of EDIX
much like the X Window System sat on top of UNIX. I wrote Edwin because
graphical user interfaces were becoming common by 1990. Edwin was
written in the E language, demonstrating that compiled code was fast
enough for performance-critical routines such as BITBLT. The background
wallpaper was generated by the precursor to MindsEye.
As the names imply, EDIX, Edwin, and the E language were all written by
Ed! That is no sillier than Linus naming his operating system