As you start decisions for an assembler project in MPLAB X
Absolute mode (not recommended)
Newer versions of MPLABX apparently support absolute mode a bit better, but problems with global variables can be caused by using absolute addressing instead of relative addressing. This is a 30 years old technique.
MPLAB X will not show variables using absolute addressing in the watch window, this is a massive problem! Rumours it may now, true??
You will need to manually set a checkbox in the project properties to tell MPLABX that this is an absolute mode project.
This is the modern recommended addressing mode.
MPLABX PIC Assembly support
MPLAB X no longer supports mpasm
There’s a new XC8 PIC Assembly “pic-as”. You need to install an up to date version of XC8 and you’ll then get “pic-as” offered as a compiler toolchain when creating a new project.