On Mon, 29 Mar 1999, Maarten ter Huurne wrote:
> At 03:43 PM 3/29/99 +0200, you wrote:
>
> >> Besides, what kind of program would leave the mapper in a different state
> >> than when it was started?
> >
> >I am busy on a muli-tasking system that cuts programs off on the
> >interrupt. It is very well possible that one program sets the mappers is
> >some state and when an other program is called, it's memory-status will be
> >saved. Therefor I need a way to read all settings:slots, subslots and
> >mappers.
>
> You don't have to _read_ them, you have to _know_ them!
> It must be clear by now that remembering what you write to the mapper ports
> is a reliable way of knowing the mapper settings, unlike reading the ports.
Not at all reliable. I don't know what all programs do with it. If they
are programmed correctly according to the rules I make for the operating
system, it will be ok. But I designed it in a way that all currently
existing programs that don't use the bios will probably work fine. And I
really don't know when they switch... But I think there is a (very slow)
way of checking it by only writing to the ports. You need to switch a bit
for that, though, so you cannot "read" all 4 mapper-states that way.
Bye,
shevek
---
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