ML-MONITOR-EXECUTABLE-WITHOUT-ANY-EFFECTS
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TOOL: 		ML-Monitor {Commodore C128}
Language: 	Assembler 
Extra:		-
Author: 	Misel Zivanovic
Note:		(C) 27th FEB 2026  - www.lived.ch, mzretro.ch
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NOTE: 	I noticed that like many decades ago, however never sweat a drop
	and tried to resolve it. I just took the workaround option.
	And that was starting it over BASIC with SYS 4864,
	instead of J1300 directly in ML-Monitor!
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Today we will resolve this matter and it came like out of the blue!
It's like destiny wanted it resolved today, so we will listen.
That means, I accidently stumbled over the solution, hehe...


EXAMPLE CODE 1:
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{Screenshots 1 and 2}

a 01300  a9 05    lda #$05
a 01302  8d 20 d0 sta $d020
a 01305  a9 0c    lda #$0c
a 01307  8d 21 d0 sta $d021
a 0130a  60       rts
a 0130b


j1300

executed with j1300 within the
ml-monitor is resulting i no changes at
all!

x
ready.

however, from basic with sys 4864, the
code is doing its thing!

sys 4864

ready.
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EXAMPLE CODE 2:
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QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ





d 1300 130a
. 01300  a2 27    ldx #$27
. 01302  a9 51    lda #$51
. 01304  9d 28 04 sta $0428,x
. 01307  ca       dex
. 01308  10 fa    bpl $1304
. 0130a  60       rts

j 1300


this one is obviously working!



CONCLUSION and SOLUTION:
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Working from BASIC
NOT working from built-in ML-MONITOR with J command
And then WORKING like nothing happend with J command

Why is that so?

I noticed this strange behavior when i tried to change the control directly at its location $d020
using the M command:

m d020 d020
>0d020 0a 0c 00 00 00 00 ff ff:......??

m d020 d020
>0d020 0b 0c 00 00 00 00 ff ff:......??

I can do all possible changes, however, the border color won't change!

...

And then i had the idea! Yes, i am good!

m fd020 fd020
>fd020 f8 f9 f1 f2 f3 f1 f2 f0:XYQRSQRP

and suddenly, changing the screen and the
border color is no longer any magic!


so what do we need to add to our
routine to make it executable with the
'j' command in ml-monitor environment?

here you go:

a 01300  a9 00    lda #$00
a 01302  8d 00 ff sta $ff00
a 01305  a9 05    lda #$05
a 01307  8d 20 d0 sta $d020
a 0130a  a9 0c    lda #$0c
a 0130c  8d 21 d0 sta $d021
a 0130f  60       rts
a 01310

j 1300


SOLUTION:
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Switching to BANK 15 is what was missing!

lda #$00
sta $ff00

is doing exactly that!
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