Holding UP-RIGHT arrows keys while pressing "R"

By santiontanon

Champion (366)

santiontanon's picture

28-03-2017, 10:23

I've noticed something weird today in OpenMSX, and I wonder if this actually happens in real hardware. Hold the UP and RIGHT arrow keys at the same time, and then (without releasing), press "R". Instead of an "R", I get a "P" and an "R". This happens both in BASIC mode, or when playing a game (I noticed it because when pressing the "R" in Tales of Popolon to change CPU mode, sometimes it was pausing the game, rather than changing the CPU).

Is this expected behavior?

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By ARTRAG

Enlighted (5826)

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28-03-2017, 10:57

It could be due to your pc keyboard
Ghosting is frequent

By NYYRIKKI

Enlighted (4649)

NYYRIKKI's picture

28-03-2017, 11:55

This is just correct emulation of MSX keyboard ghosting... This happens on every MSX due to keyboard hardware implementation.

By santiontanon

Champion (366)

santiontanon's picture

28-03-2017, 17:40

oh! ok! Thanks guys Smile

By rderooy

Master (137)

rderooy's picture

28-03-2017, 20:40

You can disable the Key ghosting in Openmsx by editing the XML file for the machine type in question.
This is documented here: https://github.com/openMSX/openMSX/blob/master/doc/keyboard....

Basically in the PPI section of the config file you need to set key_ghosting to false.

However, your PC keyboard can also suffer from ghosting, and the emulator cannot do anything about that obviously.
Have a look at this wikipedia article for more details
Rollover (Key jamming and ghosting)

By FiXato

Scribe (1246)

FiXato's picture

28-03-2017, 20:42

rderooy, I've edited your post so your Wikipedia link actually works since this forum's software does not recognise ( nor ) as part of a link. A handy way around this is to replace them with their urlencoded alternatives %28 and %29 Smile

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