#3 How to get the code to compile on Ubuntu 20.04.1 LTS

[AnC]

Use the attached Makefile in the main directory. It takes care of

1) gcc 4's new and different OBJECTS, LDFLAGS, LDLIBS order requirement (line 187) (Why change this, and break compatibility, gcc developers???)
2) adds -lz to the LDLIBS. (line 117)

You will also have to edit the qemu/qemu-git/configure-small
and around line 397 add this line:

werror="no"

[AnC]

Additionally, use the attached config.tmpl if there are no letters on the calculator's buttons.

[JJ]

Sadly, I run into some other problem. I had already installed the libgtk2.0-dev dependency in Ubuntu to compile some other projects in 20.04.4 LTS and x49gp still does not compile.

After compiling all the .o files, there are errors when it comes to the linking process in the Makefile. Output of the command is attached:

$ make > ../errors_linking.txt 2>&1

There's a bunch of variable undefined errors.

I already applied all your previous indications on changes to compile in Ubuntu 20.04.1 LTS except using the new config.tmpl.