Thanks for the reference to the Oppedahl book; I didn't know it existed but I found it on the Internet Archive. I'm glad I made a donation to them earlier this month.
Reading through the title pages I was floored when I read that Carl Oppedahl / Weber Systems was located on Mayfield Road in Chesterland, Ohio; literally a few miles away. I don't know if they're still there; I'll have to look. You always assume the experts are on one coast or another. Also found another pretty good reference: *Hidden Powers of the TRS-80 Model 100* by Christopher Morgan, (Waite Group, 1984) which describes the same topic in some detail. Thanks again to B4 Me100 for the heads-up. -CH- <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
