Victor/Jvc hc-95

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By Eugeny_Brychkov

Paragon (1226)

Аватар пользователя Eugeny_Brychkov

21-08-2022, 15:33

Reviving the thread: can not find if it is possible to know, other than looking at the turbo switch, if machine is in turbo or Z80 mode. Imagine switch is broken and is stuck in specific electrical contact configuration whatever position you move it to. How would you find out actual CPU mode?

By gdx

Enlighted (5996)

Аватар пользователя gdx

21-08-2022, 16:11

It is possible to make a small program that tests an instruction that there is not in a Z80.

By Eugeny_Brychkov

Paragon (1226)

Аватар пользователя Eugeny_Brychkov

30-08-2022, 18:05

Probably a mistake: connection of the IC007 to IC042 and then to /G inputs of IC029 (second page, quadrant G4, near Z180). If this would be connected this way, write and read to PPI would only work only when A=0ffh. Not sure how JVCREQ makes a difference here as it is sourced at the pin 31 of the unnamed connector on the page 3. Probably /JVCREQ is always high in Z80 mode? But looking at the Z180 datasheet it also puts contents of A onto the A15-A8, therefore it will also not work properly in Z180 mode this way if /JVCREQ is low.

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