I found a number of hits there from GOOGLE, but found, also, that they were apparently out of date and inaccessible. A traditional macro-assembler is a wonderful tool, but probably inappropriate for inclusion in a debug monitor intended to reside in the processor's on-board ROM. I'm wanting to stuff a debugger with line-by-line assembly/disassembly capability comparable to MSDOS' DEBUG or, at least, CP/M's DDT, to coreside with a relatively powerful debugger in the on-board FLASH in an 89C420. This part can run the debugger from its internal ROM, yet, by means of a little SFR trickery, run application code in a full 64K code space map in external memory, together with a full (almost) 64K external data RAM map as well. I find that notion appealing. That way I don't have to make last-minute tweaks tethered to a PC, but, rather, can operate in native mode. Dick ----- Original Message ----- From: "Glen Goodwin" <acme_ent(a)bellsouth.net> To: <classiccmp(a)classiccmp.org> Sent: Friday, March 22, 2002 10:34 PM Subject: SIMTEL (was Re: Source code for 805x line-by-line assembler?)