Joysticks: MSX vs CPC/CPCplus

Master (222)

03-01-2020, 19:04

Hi
Since recently I'm having problems with my eyes (well, a bad joke) I have been working trying to repair a cpc6128plus computer. Today's step was the control pad. What I usually do is take one of those NES control pads spares I've got here and adapt them to the computer I want to use, mainly MSX.
But, until today, I believed that using a cpc plus pad on a MSX was SAFE and compatible, but any of my msx pads I've adapted works on that cpc6128plus. I've found that the ground I used on my msx pads is the pin9, while the one used on cpc is the pin8. I tested it and yes, it works, on cpc and also con MSX.... while MSX uses pin8 for OUT.
So, my questions are:
A) is safe use a cpc+/gx4000 controller on a msx?
B) wich option is the best for GND on msx controllers, pin8 or pin9?

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Van sd_snatcher

Prophet (3677)

04-01-2020, 01:06

Tip: the schematic of the standard MSX-Joytick is shown here.

Van makinavaja

Master (222)

04-01-2020, 09:13

sd_snatcher wrote:

Tip: the schematic of the standard MSX-Joytick is shown here.

I know, you can find that info easily,. but my question isn't solved yet. I mean, on that link it says the cpc464 controllers are compatible (then, also 6128 and 6128plus are too) but, I repeat: they use pin8 as GND, not pin9.
So, or that wiki has a mistake, or using pin8 as ground is safe on MSX.

Van gdx

Enlighted (6449)

04-01-2020, 09:34

Only controllers for Amstrad CPC with two buttons work on MSX.

http://wiki.icomp.de/wiki/DB9-Joystick

Common MSX controllers can use the pin 8 or 9 but not the both of the same port because pin 8 is not the GND.
Use pin 8 preferably. The only case where you must necessarily use the pin 9 is to make a controller compatible with the FM-Towns.

Van jltursan

Prophet (2619)

04-01-2020, 10:30

And here you'll find some nice info about this subject: https://www.msx.org/forum/msx-talk/hardware/joystick-port

Van hamlet

Scribe (4106)

04-01-2020, 11:19

I do game with a CPC gamepad from time to time and I haven't noticed any problems so far. This pad is from another MSX user, so I don't know if it is still original.

Van sd_snatcher

Prophet (3677)

04-01-2020, 14:32

makinavaja wrote:

sd_snatcher wrote:

Tip: the schematic of the standard MSX-Joytick is shown here.

Please take some time to analyse schematics in that page carefully. It shows that the common pin for all button on the MSX-joystick must be the pin-8.

On the MSX, the buttons are not connected to the GND, but instead to a selection signal that comes from the pin-8. This is identical to the way that the MSX-keyboard works, but the matrix has only a single line.

It was made this way by design, to allow expansions and interoperation with other types of the devices on the same ports, since they're General Purpose Ports and not only joystick ports.

Van makinavaja

Master (222)

05-01-2020, 10:45

Hi!

gdx wrote:

Only controllers for Amstrad CPC with two buttons work on MSX.

http://wiki.icomp.de/wiki/DB9-Joystick

jltursan wrote:

And here you'll find some nice info about this subject: https://www.msx.org/forum/msx-talk/hardware/joystick-port

That's the info I needed.
I'm not an electronic engineer, all I do in my house is reading info and "understand" the basics, but sometimes it doesnt happens: Thats why I believed that GND was the correct option,... and OUT for my was an strange pin.
Anyway, thank you everybody for yous answers :-)