Re: Sweet16 and GS/OS Booting

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

Toinet <antoine.vignau@laposte.net> wrote:

> In the ProDOS file,
> - the first issue is related to the settings of the registers.
> The ProDOS file assumes a full 16-bit native mode when a full 8-bit
> emulation mode is sent when launched from ProDOS 8 / BASIC.System (P8/
> BI)

No it doesn't. Any PRODOS file (including the GS/OS loader) is normally
loaded by the boot block, which is running in emulation mode. The boot
block is the same for ProDOS-8 and GS/OS boot disks.

> - the second issue is related to the boot device identification.
> The ProDOS file awaits the boot slot number in $7F8 which it does not
> get when started from P8/BI

This is the main issue: the PRODOS file depends on information left by
the boot block to identify which slot it booted from. I don't recall the
details (I thought it was a zero page variable.)

Launching a PRODOS file via the BASIC.SYSTEM "-" command tends to work
on a real IIgs, because the ProDOS block drivers happen to leave the
right value in the appropriate locations. Perhaps the Sweet16 drivers
aren't doing the same thing.

I'd have to dig out my ProDOS manuals to confirm the details.

-- 
David Empson
dempson@actrix.gen.nz