Just after a bit of advice really.
Let me state a few things, I am not a programmer, in that I only do this for a bit of a challenge to the Gray matter somewhere at the top of my body, it is good when things work however. When recently playing with some old IFR test gear I am again finding most things are processor based and this has led to me digging out old projects of many years ago.
I have two Atmel devices I am interested in the 8951/2 series, i have a few chips left over and boards lying around so planning to play with them.
A couple of TUXGRAPHICS boards that use the Atmega328, so nothing of any real power.
The last time I touched the 51 stuff was in 1997/8 all done in assembler AESM51 and I used Equinox Micro ISP for test debug and an old parallel port programmer for final programming. which I still have the hardware, but the old computers that used to run them like Win 3.11 and Win95 have long gone.
For the Atmega, I did have Studio 4 at one time so must have made it up to C programming and used some form of In circuit programmer, an SKT500 thing? that I am still looking for.
I use Suse Linux computers at home so would like a Graphical IDE that would run in linux, but if needs be can use windows as I still have XP and even Win10 although I hate with a passion the screen layout and yearn for the old 95/98 desk tops and stuff of years gone by.
So anyway getting down to it. What would you suggest for an old f**t like me and an 'old peoples home' is not the answer I am looking for! by way of programming tools and debuggers.