System variables (again!)

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By Bengalack

Hero (580)

Bengalack's picture

14-05-2022, 07:57

Great insight here! Thanks. But... if you are not using BIOS, and use your own ISR, and you never return from your program until there is a reset(as is it a rom/cartridge), I can't see how the ram "hi-jacking" affects anything. If there is a problem with this approach, it is the choice of not using BIOS-calls. This may cause future incompatibility... which is a fun thing to discuss regarding a retro-machine Smile Yes, I know about Nishi's latest works... 30 years later Smile

By Micha

Resident (50)

Micha's picture

14-05-2022, 11:11

Bengalack wrote:

If there is a problem with this approach, it is the choice of not using BIOS-calls.

Are there actually any machines that don't use the "standard" ports for the VDP, PSG, keyboard and joysticks? Is there an overview or a list on this?

And the other way around: how much software/games are out there that handle hardware directly without using BIOS calls ?

By Bengalack

Hero (580)

Bengalack's picture

14-05-2022, 17:22

Micha wrote:
Bengalack wrote:

If there is a problem with this approach, it is the choice of not using BIOS-calls.

Are there actually any machines that don't use the "standard" ports for the VDP, PSG, keyboard and joysticks? Is there an overview or a list on this?

Other people here know this area better, but AFAIK there is this, and the like: https://www.msx.org/wiki/Neos_MA-20

By Bengalack

Hero (580)

Bengalack's picture

03-07-2022, 10:31

Micha wrote:

If you do have your own ISR and you don't use BIOS calls and you have all other interrupts disabled then it should be safe to use F380-FFFE...

What "all other interrupts"? I'm on IM1, and purely running my own code on 0038h.

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