Re: GEMDOS from VBL

[Julian Reschke-FJR010 <Julian_Reschke-FJR010@email.mot.com>]

stehlik@cas3.zlin.vutbr.cz%INTERNET wrote:
> 
> On Sun, 14 Jun 1998 17:04:31 +0200 (MET DST), Johan Klockars wrote:
> 
> JK>First a rather fundamental question:
> JK>
> JK>  Do you really need the VBL at all for Clocky under MiNT?
> 
> Clocky is a general utility that should run under all available
> operating systems. There's no OS-specific code yet.
> 
> JK>> a little update of my previous message: calling Malloc(-1L) from VBL
> JK>
> JK>I haven't looked that much into the MiNT code, but it is by no means
> JK>obvious that all parts of GEMDOS should be reentrant.
> 
> I haven't looked into MiNT code at all, though I seem to remember that
> the re-entrance of GEMDOS was one of main advantages of MiNT over TOS.
> 
> JK>After all, MiNT
> JK>doesn't multitask once supervisor mode is entered and the original OS
> JK>code is still used for some things.
> 
> yes, that's right.
> 
> JK>As was said before, OS calls from interrupts are often a very bad idea.
> 
> But how one can write TSR then? I need to do a lot of things, and system
> variables are not documented. How would you, for example, changed
> current keyboard layout mapping? The system variables are undocumented,
> so I need to call OS call from interrupt.

You can get the XBIOS character pointers during the installation phase
and store them somewhere. No need to call the OS from the interrupt for
that.

Regards, jr