Assembler IDE/Simulator for beginner

You might want to check out the open source 8085 simulator "GnuSim8085", it's specifically meant to be used for educational purposes, and it was in fact written by student while preparing for his exams. It runs on both, Linux and Windows.

WinApe is a good emulator of an Amstrad CPC. The Amstrad CPC was a Home Computer produced in the 80's. It used a Z80 as its CPU. Using the emulator you can display a lot of the internals while programming. It includes a debugger and a disassembler for Z80 code.

I've found a few bits of software that suggest they might do this - but they either refuse to compile, or don't seem to work properly. Has anyone got any suggestions?

Write one. You're best off picking a nice, simple instruction set (Z80 should be perfect). I remember doing this as a first-year undergraduate exercise - I think we wrote the simulator in C++ and simulated 6800 assembly, but really any language/instruction set will do.

The idea of "learning assembly language" these days is to get the idea of how computers work at the lowest level, only a select few (compiler writers, etc.) have any real reason to actually be writing assembly code these days. Modern processors are stuffed full of features designed to be used by compilers to help optimise code for speed/concurrent execution/power consumption/etc., and trying to write assembly by hand for a modern processor would be a nightmare.

Don't fret about getting your application production-ready unless you want to - in all likelihood the bits of software you've found so far were written by people exactly like you who wanted to figure out how assembly works and wrote their own simulator, then realised how much work would be involved in getting it "production ready" so the general public could use it.

If Your are on windows 8085 Simulator is the best choice.

It user interface is excellent than any other simulator. Also this simulator provide live view of memory map very time(also while in the execution).

But this one does not support Windows 98 or lower for that you need to check other simulators like GNUSim8085.