what is this message in openmsx?

By _ThEcRoW

Resident (60)

_ThEcRoW's picture

28-04-2013, 14:41

"The running MSX software has set unsafe PSG port directions. Real (older) MSX machines can get damaged by this."
I usually test romfiles before putting them on my megaflash, as is faster testing on openmsx, but on some roms, i get this message. It happens with some originally released rom games, as well as tape/disk conversions to rom.
The thing that bothers me is if i could get my msx damaged, and being the hardware old as it is, i won't risk it unless some of the openmsx developers say what is exactly the problem with such roms.
Anyone got a clue?.
Thanks in advance.

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By PingPong

Prophet (3301)

PingPong's picture

28-04-2013, 15:07

PSG in msx also handle joystick ports.
if a sw write some values into psg registers, then the psg could be damaged because there will be a short circuit.

Normally most msx models have a hw protection to avoid this, so there is no problem, but if you own a model without this protection the psg output pins can be damaged.

By _ThEcRoW

Resident (60)

_ThEcRoW's picture

28-04-2013, 15:18

My machine is a sony hb-75p. How can i know if my machine has such protection?

By PingPong

Prophet (3301)

PingPong's picture

28-04-2013, 15:33

unfortunately i do not know.
what i know, is this machine have a true psg chip inside, so there is a good possibility to damage it.
Others machines have psg cloned into some other chip, called msx-engine. In the latter case there is a relatively low possibility to damage it.

By hap

Paragon (2019)

hap's picture

29-04-2013, 11:33

I wonder if anyone has ever practically broken an MSX like this, or is it just a theory from reading schematics? I've never heard of it, seriously. There are dozens of old MSX games with this bug.

By PingPong

Prophet (3301)

PingPong's picture

30-04-2013, 00:25

hap wrote:

I wonder if anyone has ever practically broken an MSX like this, or is it just a theory from reading schematics? I've never heard of it, seriously. There are dozens of old MSX games with this bug.

a short circuit is not a *theory*.

By hap

Paragon (2019)

hap's picture

30-04-2013, 00:43

a short circuit is also not a *practically broken msx*. Hannibal

By PingPong

Prophet (3301)

PingPong's picture

01-05-2013, 09:35

hap wrote:

a short circuit is also not a *practically broken msx*. Hannibal

Try to explain this concept to _ThEcRoW if he broke its computer. ;-)
The assumption that you have never seen a broken msx for the improper use of psg ports does not ensure nothing.
I also remember that some one, time ago, complained about some joystick port failure. I also remember that the problem was related to psg ports.
Now, because it's very unlikely that the psg itself can broke without a specific reason, it's likely that the problem was due to the invalid set up of psg registers.

By _ThEcRoW

Resident (60)

_ThEcRoW's picture

21-05-2013, 23:24

Seeing the posts in the thread , i think i will avoid the programs witha that bug in the real machine. I always
test the roms in openmsx before puttting it on the megaflash, mainly to check if it is ok, so i will avoid the ones
where this message is displayed.
Thanks!!!!