Re: AppleTalk / Interrupts / ProDOS 8 / DOS 3.3 Launcher

[dempson@swell.actrix.gen.nz (David Empson)]

In article <1993Apr7.223832.3208@fawlty.towers.oz.au> johnmac@fawlty.towers.oz.au (John MacLean) writes:
> 
> One question though, will these interrupts work in a similar way on
> a //e with a workstation card, or will the $3FE or $BF?? vectors be
> needed?

No.  The IIe workstation card will require interrupts going through
$3FE and ProDOS interrupt handlers.  The same apparently applies to
the Ethernet card (when it is released).

> >Yep, DOS 3.3 cold start initializes $3D0-$3FF.  I hope you're saving
> >and restoring this area (at least $3F0-$3FF).
> 
> No I'm not - although I could quite easily. A few thoughts:
> If there were interrupt routines in ProDOS 8, they'd crash pretty
> quickly when DOS 3.3 got in memory.

I meant that on return to ProDOS you should restore their previous contents.

> Does ProDOS 8 quit code initialise these areas?

No.  ProDOS-8 initializes them when it starts up, and BASIC.SYSTEM
probably reinitializes some of them.

The RESET vector is the only one that the quit code will change.

> Thanks for the detailed explanation, it really helped.

Glad to be of service.  The IIgs Firmware Reference manual would have
saved you a lot of time.


A suggestion: you could completely avoid removing the ProDOS-8 global
page if you used a patched copy of DOS 3.3's RWTS, and disabled the
INIT command (provided you aren't already using this code area in your
patched version, of course).

I did this a couple of years ago, but my DOS3.3 program only supports
genuine 5.25" DOS 3.3 disks, not disk images.  There are a few patch
routines near the end of page $BF, but I moved them down into page $B6.
-- 
David Empson                                                               
dempson@swell.actrix.gen.nz    <--- Note my new E-Mail address!            
Snail mail: P.O. Box 27-103, Wellington, New Zealand