General Category > Software related

6128 Plus BASIC problem?

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Animalgril987:
Hi Peter.
No probs :D
But I wouldn't have thought the messiness in that area of the program would cause it to fail on the Plus. There must be something in the m/c code the Plus doesn't like..
I don't have a plus, so I can't test it myself.


Alan.

dragon:
Amstrad remove some commands in plus firmware. Causing some address directions change.


So some programs that try access the firmware directly using calls can fail, because they call wrong direction..


Try load it with this cartridge.


https://www.cpcwiki.eu/imgs/7/7a/Basic_%28F%29_%28White_Label%29.zip

Animalgril987:
Thanks for the info, Dragon. :D

ComSoft6128:
Never knew that, thank you :)

Animalgril987:
After some investigation, it turns out that  the machine code does a fair amount of reprogramming the 8255 PPI.


As the Plus ASIC emulation of the PPI is not perfect, the Plus will throw a wobbly ( usually no keyboard response or sound).
The exact problem is a couple of points where the PPI control register is reprogrammed.
In a real PPI, this clears the output registers, but they are not cleared in the emulation.


I don't have a plus to test,it on, but I think modifying the program to send 0x00h to PPI ports A and C immediately after the control port writes SHOULD make it Plus friendly.


Alan.



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