What I meant was not that the AIM65 was CMOS, but rather, that the ROCKWELL version of the CMOS 6502 was different from the NMOS version sold by MOS Technology. One way of telling whether the assembler is written for the NMOS or the CMOS version, would be to have it assemble a source file with a few of the CMOS instructions in it and see how it handles them. What's more, the unimplemented opcodes in their CMOS processor were all implemented as NO-OPs while the NMOS version had that widely known (or at least heard-of) set of odd-ball (undocumented) instructions Hans Franke wrote about a month or two ago. You just have to look at the processor to determine whether it's a CMOS processor, but the assembler could be for either processor. The BASIC is probably the version for the NMOS part. I assume that the early release number is all one needs to tell that. Anything made after 1983-84 could go either way. Dick -----Original Message----- From: Joe <rigdonj(a)intellistar.net> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Tuesday, May 25, 1999 2:58 PM Subject: Re: AIM 65 question have interpreter current Anyone