Re: Software for MS-DOS 1.25

From: Michał Pleban <*lists_at_michau.name*> Date: Tue, 10 Oct 2017 17:45:11 +0200 Message-ID: <59DCEB07.7050507@michau.name> · lists_at_michau.name

Hello!

smf wrote:

> However it should be possible to come up with a scheme where you
> virtualise the applications int 08h call from the int 0ah handler as
> well. The application will call through to the real int 08h, which you'd
> have to detect and shunt back to the int 0ah instead. This is probably
> only worth doing if that is the only thing stopping an application from
> running though.

You could do that in the INT 0Ah handler as well. Just look at the INT
08h vector - was it overwritten by the application? If yes, then call
it, if not, don't call.

Then perhaps the code calling 6509 would overwrite the vector back just
for the time of the call, and then switch it back.

> What rate does 0ah fire at?

It's the TOD clock. I can't remember whether it's 50Hz or 60Hz on the 710.

Regards,
Michau.

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