Conversation

I had a subtle-seeming but ultimately stupid problem with my CP/M project and was forced into using ED.COM.

ED.COM is a 1960's paper tape editor, like unix ed, that you Yank lines from the input file into the in-memory work buffer, and Put lines to the output file. Unlike paper tape editors you can actually go backwards in the file.

(In the 1970s, I had a junk Varian 622/I minicomputer, all paper tape, on which I actually edited programs using the paper tape editor. You pressed a front panel switch (!) and it would load ONE LINE of text to core; spacebar advanced through the line, printing on the tty; another letter would insert, delete, etc; another would punch the edited line. You could only go forward. Backwards required punching out the rest of the tape and physically placing it in the reader. ed, ex, and vi still contain this paradigm within them.)

Its kinda awful, but very easy.

The ED.COM binary is 6656 bytes of 8080, and that's rounded up to the nearest 128 byte sector.

There is something fascinating and instructive about th3e brutal but elegant *spareness* of ED.

And after solving my Stupid problem (having to do with Side Effects of the absolute value of a JMP instruction address in low memory) i can now run PMATE, the text editor I used 2nd longest, after vi/vim.

Today was a good programming day'; solved a bunch of months old bugs that all had the same cause which was dumb and easily fixed once I actually delved deep into a program with SID, instruction y instruction. Hadn't done that in years.

#cpm #retrocomputing