Default state of TH pin

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TmEE co.(TM)
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Default state of TH pin

Post by TmEE co.(TM) » Thu Jun 11, 2015 12:59 am

...is different on TMSS and non TMSS hardware.

On non TMSS hardware the pin defaults to "1" state while on TMSS hardware it defaults to "0" state.
I was debugging couple ROMs sent by someone who made few demos in the early 90's and they all had the problem where controller input wasn't as expected. These demos didn't initialize the controller ports and as a consequence they only worked proper on MD1 VA4 and older, while failing on newer stuff.

It seems all emulators (that I tried) emulate the TMSS hardware behaviour.
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HardWareMan
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Post by HardWareMan » Thu Jun 11, 2015 4:47 am

There is a programmer's golden rule: no one will do initialization for you. So, to rely on the default state is fraught with errors. Conclusion: drive out such programmers away from MD.

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