Undocumented fields of IOREC structure...

[steve@mctavish.demon.co.uk (Steve Woodford)]

Hi Minters,

In various places (eg. xbios.c biosfs.c) MiNT pokes about with a couple
of undocumented locations in the IOREC structures for the extra serial
devices like Modem2, Serial[12]. These appear to be copies of WR3 and
WR5 of the SCC chip.

For reasons which will become apparent, I need to know if these are
indeed used this way and if there are any other 'extra' fields in the
IOREC structure which are commonly used.

Now before I get toasted for wanting to know about undocumented
features of TOS; I'm in the middle of porting MiNT to another
platform (ok, so I'm a masochist, but I had this kit lying around)...
Since I'm also having to write a bios, and minimal xbios/gemdos, I
need to know about such things. In this case it's easier since the
new platform uses the same Z8530 SCC chips.

In case anyone was wondering, the platform in question is a
Motorola MVME-147S VMEbus card. It has a 68030 @ 25Mhz, with FPU,
4 serial ports, parallel printer port, SCSI port, an ethernet port
and 8mb RAM onboard. Add to that various other VMEbus cards like
more memory and you can see why I'd like to make it earn its keep! ;-)

So far I have a complete (appart from this IOREC thing) working BIOS
emulation, and almost the bare essential XBIOS and GEMDOS. I've
incorporated minixfs into MiNT (or VMiNT, as I'm calling it) so
for now I won't have to write a full GEMDOS with a TOS filesystem.

I'll keep this list posted as to how things go. Needless to say,
there will probably be other 'gotcha's that I'll be asking about. :-/

Cheers, Steve