The MPLABX v5.40 IDE still has a lot of problems.
The pic-as(v2.20) tool chain is a nightmare.
This is the code I could get to work:
; File: main.S
; Target: PIC10F206
; Author: dan1138
; Date: 2020-08-14
; Compiler: pic-as(v2.20)
; IDE: MPLABX v5.40
; Depends on files:
; Example project for the PIC10F206 controller using the pic-as(v2.20) tool chain.
; Add this line in the project properties box "pic-as Global Options -> Additional options":
; -Wa,-a -Wl,-pStartCode=0h,-pOscCalVec=1ffh
; Include target specific definitions for special function registers
; Set the configuration word
config MCLRE = OFF, CP = OFF, WDTE = ON
#define LED_GPIO 1
; Declare one byte in RAM
Counter: DS 1
; Simple test application that toggles
; GPIO bit x on every wake from sleep.
; The WDT timeout is at least 1280 milliseconds
; and at most 3968 milliseconds, will typically
; be about 2300 milliseconds. It depends on the
; temperature and the VDD voltage.
movlw 0xDF ; Use FOSC/4 as TIMER0 clock not GPIO2
clrf CMCON0 ; turn off comparator
bcf OSCCAL,OSCCAL_FOSC4_POSITION; Do not drive GPIO2 with FOSC/4
andwf GPIO,F ; set all output bits to zero
xorwf GPIO,F ; Turn on LED
incf Counter,F ; Increment the Counter value
sleep ; Wake from sleep results in a reset
goto Loop ; Hang here waiting for a reset
; In the PIC10F206 the factory calibration for
; the onchip oscillator is stored as a MOVLW 0xnn
; opcode as the last instruction of code space.
; On RESET the PC is set to all ones and this
; opcode is executed, then the PC rolls over
; to zero and the first opcode of the application
; will execute.