the only real difference between what you use and an MCU-resident monitor program is that you use a monitor program that runs on your PC and controls the MCU via JTAG. I don't doubt that this is better, as it doesn't take up MCU memory space, but (a) relatively few 805x-core MCU's provide the JTAG interface, and (b) very few of the ones that do will work in exactly the same way, so there's considerable learning curve whenever he switches from one MCU to another. Since he's likely to be using two different MCU's, albeit from the same family, that could present a problem.

Since the original question was one regarding a family of MCU's that doesn't offer the JTAG support YOUR PREFERRED METHOD requires, and since the Original Poster has made it clear that he doesn't want to use a bleeding-edge version of the 805x family, don't you think it reasonable for the Original Poster to consider alternatives that DO work with his desired MCU?

With Ultramon51, just as an example, he can set breakpoints, modify register values, edit memory content, single-step, all of which I suppose you do with JTAG. Using Ultramon51 he can also load code using XMODEM protocol, he can trace program execution, he can single-step, he can enter, assemble, debug, and disassemble code resident in his MCU's memory. Could you do that using his desired family of MCU's without resorting to other, third-party resources? Probably not.

Since he's made it clear which MCU he prefers to use, how would you suggest he do those things without an MCU-resident monitor program?

BTW, the DS89C450 came out in 2000. Didn't the SiLabs parts you were using also come out about then? There are numerous reasons why one might prefer the Maxim/Dallas families that have dual data pointers over the SiLabs parts that don't. That may not be a deal-breaker, but it is a consideration. Since he's not dealing with analog signals, he probably doesn't care about the data acquisition capabilities of your preferred series, even though he doesn't have to use those features. Why, then is it that you always insist that your way is the "best" way? You've not made that clear. Maybe you have an argument that will persuade him.

RE