First I just want to say that I'm still looking for 'copies' of two RCA publications: MPM-232 Operator Manual for the RCA COSMAC DOS Development System (CDS III) CDP18S007 MPM-233 Hardware Reference Manual for the RCA COSMAC DOS Development System (CDS III) CDP18S007 If you have one or both or know where to order these manuals, please let me know. O.K. I said: I dug my copy out and yes there is source listings. Paul took RCA's CHIP-8 interpreter and modified it for the ELF. In this book ("Programs for the COSMAC ELF: Interpreters"), he starts with a subset interpreter that has 10 CHIP-8 instructions and is intended to run on a 256 byte Basic ELF. Then he lists the full Elf CHIP-8 interpreter with all 30 instructions. This is intended for a 4K Super Elf with 1861 video, but it can run on a 1 1/4K Elf. "It is also possible to use CHIP-8 in the 1 1/4K ELF's described in the articles in Popular Electronics, but to do so is very tedious unless the switches are replaced with a latched decoded keyboard." He also demonstrates with listings, how to extend the CHIP-8 instruction set. I can send you a copy of this book, it's only 31 pages. I also have one of his other books called "Programs for the COSMAC ELF: Music and Games". ----------------------------------------------------------- Fun Fact of the Day Did you know that a windowing graphical user interface was available for S-100 bus in 1979? See the product review in Popular Electronics Aug 79 page 74. ----------------------------------------------------------- ========================================= Doug Coward Press Start Inc. Sunnyvale,CA =========================================