Walther Miller, the story?

I purchased one of their cartridges back in the day (Miller Graph) and I can tell the quality was not very good.

I remember I found the cartridge was actually running a BASIC program because I could stop it using CTRL+STOP.

The available info is close to zero. I've found references about there's some "secrecy" around them, seems that someone don't want to live again these years.

This is the more detailed info I've been able to find (in Spanish): The wonderful world of Walther Miller

The last paragraph summarizes a bit how the company was perceived back then...

IIRC, it just sets in pages 0 and 1 the same subslots than in pages 2 and 3. So it is some kind of "universal poke" that is executed after every BASIC command.

di
ld      a, (#FFFF)
cpl
and     #F0h
ld      b, a
rrca
rrca
rrca
rrca
or      b
ld      (#FFFF), a
ei
ret

The cartridge was advertised as:
"Multimiller is an Msx-1 and Msx-2 operating system reconfigurator, allowing you to get 100% performance from your personal computer. Thus eliminating any hardware problems. Be ready to use all the software of the market from this moment, since you will be able to use the one of Msx-1 for Msx-2"

But what it basically does is a POKE -1,x

Here is the BASIC program of the cartridge:

10 DEFUSR=&H8100:A=USR(0):FOR X=1 TO 1000:NEXT
20 SCREEN 0:WIDTH 40:COLOR 15,4,4:KEYOFF:CLS
30 PRINT"MULTIMILLER"
40 PRINT"Copyright 1987 WALTHER MILLER"
60 PRINT"Ready"
70 DEFUSR=&HBA00:A=USR(0)

The asm routines draw a intro screen, verify that the code is run from ROM and patch the hook at #FF0C to run the "poke" after every BASIC command.

You can find their dangerous joystick here: https://en.todocoleccion.net/video-games-consoles-msx/joysti...

Unfortunaly all the pictures are degraded by horrible watermarks.

Joystick without base, uses sensors to detect movement. The sensors probably use dangerous mercury switches to sense orientation. Not something you want children to play with.