Mark, I have used the 12C509 in a product we produce and used the JW version for debugging purposes. Also used the internal oscillator and bit banged for a 9600 baud serial output (out only). The only thing I ran into was a difference in oscillator speed between the JW and SMT parts (enough to affect the serial out timing). Discovered this was due to a manufacturing date series on the SMT parts, reported here on the piclist,. Also use "ICSP" on these and everything seems to be working fine now. Did not get into the "A" versions yet. Don't know if this helps or not. Mark Willis cc: Sent by: pic Subject: 12C508/9, 12CE518/519 ti ps microcontroller & tricks? discussion list 10/06/99 11:39 AM Please respond to pic microcontroller discussion list Anyone have a good web page with some good 12C508A or 509A hints? Haven't used these yet, am starting a project. Need the low cost 16C622/JW's just aren't the same as these! Will plan to use internal oscillator, again for low cost. Making a network of these with a push button apiece, and probably 1-wire signalling between them (Push the push button, the appropriate ones sound off through a Piezo disk (Differential drive), 9V power off the RJ-11 cabling, I'm thinking, 78L05 at each chip, maybe?) Should be a fun little project. They want some custom sounds, I'll code THOSE on a 16F84 or an XT or something, I think, & then move those to the /JW part. Mainly looking for any "Gotchas", besides the Spec Sheets. Any problems in coding for the 12CE519/JW, then transferring some projects to a 12C508A, for example? (It's a whole buck cheaper ) Client wants 'em CHEAP, and ubiquitous. Due to the EEPRom, may just go with the 12CE519/JW parts, does look like these're all reasonably similar (But then, I have -just- started to read the Spec sheets in depth!) Mark