Can someone help me out with Z88dk?

They also have a forum: https://www.z88dk.org/forum/index.php

You could also try asking me.

@WORP3: You may want to tell first what you are trying to achieve, that way maybe somebody who knows their way around z88dk can give you some help. I've used it a couple of times, although I didn't need to change the compiler config/crt.

That’s something i can do in the upcoming week. For now it must run on a basic empty 64K z80 system, hardware is all custom so no need for support library. Preferable an open source compiler so it’s possible to make changes when needed.

I'm pretty handy with z88dk. What do you want to know?

The z88dk project's wiki has a page that specifically talks about generic z80 code generation starting at address 0. Here's a link to it: https://github.com/z88dk/z88dk/wiki/NewLib--Platform--Embedded. z88dk contains two different compilers and two standard clibs. sccz80 is their original C compiler which can compile more obscure edge cases of the language. zsdcc is a version of sdcc modified to work with z88dk's libraries which can make slightly faster code and has options for using different registers but has fewer features. As for the clibs, the classic lib is the original one that covers many different z80 based platforms but involves more adhoc functions written in assembly. Newlib as the name suggests is newer and more of it is written in C itself with the aim to be more conformant to the C11 standard, but it only supports a few different platforms. One of which is for non system specific z80 output though. A lot of the improvements of newlib have also now been merged back into the classic clib.