In January 1979, Byte Magazine's Language Forum contained the article, "IPS, An Unorthodox High Level Language."[1] The article described IPS, a language based on Forth, but with the word names translated to German. Thus, Forth's SWAP became VERT, short for vertauschen. The intriguing article concluded with a reference to Charles Moore's 1974 paper, "FORTH, a New Way to Program a Minicomputer,"[2] which was discussed on HN in 2022.[3]
I had recently assembled a Quest Electronics Super Elf computer[4] with an expanded memory size of 4 KB. The IPS article mentioned implementations under 6 KB for 8080, 6502, and RCA COSMAC microprocessors, so I thought Forth might fit. The Super Elf included an 1861 video display controller chip, with a resolution of 64 x 128 pixels (big pixels!). I designed a font of 3 x 5 pixel characters to provide 21 lines of 16 characters. Good luck distinguishing M, N, H, U, and W without some context. I bought a (possibly surplus) keyboard from Radio Shack and screwed it onto a wedge of wood to achieve a usable typing angle.
Moore's paper described about 75 Forth words. I wrote them on index cards and jotted down Forth definitions or RCA 1802 assembly code. I wrote an 1802 assembler in Fortran to ease the conversion into 1802 machine code. I still have the printouts and punch cards in storage.
Development proceeded slowly. During a break at work, I would punch my assembly code for a few Forth words, run the assembler, and bring home the printout. That night I would load previous work into the Super Elf from cassette tape, key in the new words (and changes) via the Super Elf's hex keypad, and save back to another cassette tape. Then I would test the new Forth words and note any changes needed on the printout. Lather, rinse, and repeat until, at last, it all worked.
The finished Forth system consumed a little more than 3 KB of the 4 KB of memory. User programs, data, and Forth stacks occupied the remaining memory. The R key stuck. The @ symbol was a 3 x 5 pixel blob (this is the very important Forth memory fetch operator). But it worked!
I demonstrated the system at the local personal computer club--spun off from the local ham radio club. Based on their enthusiasm, I advanced to developing tinyForth[5] for the TRS-80, a story for another day.
[1] https://archive.org/details/BYTE-MAGAZINE-COMPLETE/197901_By...
[2] https://articles.adsabs.harvard.edu/pdf/1974A%2526AS...15..4...
[3] https://news.ycombinator.com/item?id=33134663
[4] https://www.oldcomputermuseum.com/super_elf.html
[5] https://archive.org/details/80-microcomputing-magazine-1980-...