knudsen@ihnss.UUCP (06/29/83)
Most Coco hackers know that the system's speed can be upped by about 40% by doing POKE &HFFD7,0 (or storing anything into HEX FFD7). However, the various manuals warn against poking to FFD9 also, which fully doubles the speed. In particular, transparent RAM refresh goes away, along with the video display. However, some local guy (Ed M) tried it anyway, and it works! In fact, it doubles speed of all-RAM programs (i.e., machine code); the old 40% job did nothing for these. Apparantly the SAM chip steals the bus once in a while for refreshes so the RAMs stay up. Yes, the screen becomes a blizzard, but anything you've output while in double-speed mode will be there upon "re-entry". NOTE: You must work your way up and back down by going thru the FFD7 poke first (do it last on the way down, I mean). Motorola does point this out in the 6883 (SAM) specs. So, let's hear some serious music & speech synthesis out there! mike k (PS: no insult intended to the great speech & music work already done by Coconuts!)