The very first 6800 I bought came with a failing carry between the two bytes of the 16-bit registers. Very disconcerting as it was the first micro I had ever made. However the supplier replaced it no questions asked... Dave Wade G4UGM Illegitimi Non Carborundum

On 2/22/12 2:19 PM, "Dave" <dave.g4ugm at gmail.com> wrote: I hadn't thought about this in a long time: I once worked on what we would now call an embedded system, that did video generation for cable TV channels. The system was based on the 6800, and we learned that there were particular product runs where you had to insert a NOP before a SEI (SEt Interrupt mask) or the SEI would fail. It bothered me no end at the time - it just seemed *wrong* to waste precious working store and processor cycles! The file system (on 8" floppies) was also sequential in allocation, so it was 'best practice' to immediately purge a file you didn't need anymore. If you forgot, then N new files later someone had to run a purge that relocated blocks to deal with fragmentation (holes), very very slowly. The assembler didn't spool its print output, either, so we ran full builds as seldom as possible, preferring to patch in the EPROM programmer when we could. Ah, those were the days?. -- Ian