Time to set some things straight here:
(and would you guys/dolls please change the subject of your messages
when this changes?)
> >
> >MSX1 and slotexpander... Some how I don't think so...
>
> Why not? After all, the slot expander is switched using memory mapped I/O
> at $FFFF. MSX1 can do that as well.
> Note that the MSX1 BIOS doesn't support slot expansion, though. Which means
> that only cartridges in the first subslot will be recognized by the BIOS.
BULLSHIT !!!
MSX-1 and expanded slots are perfectly 100 % compatible, AND
supported by BIOS-routines:
-MSX-1 Technical Databook even shows a sample circuit diagram for
expanded slot select control
-MSX-1 BIOS routines dealing with slotswitching have the same
'specifications' as MSX-2 counterparts, and INCLUDE sub-slot
switching/reading/writing/calling
-MSX-1 and MSX-2 slotswitching-routines ARE essentially the same, I
think I figured out some minor differences once, but that's just
details (performance-related or such), sub-slot use is absolutely
FULLY supported by MSX-1 BIOS routines
-I had a Philips NMS 8020/40 once (with expanded slot 3, like the
Philips MSX-2 models). Apart from having to add this famous POKE -1
to several game loaders, which wouldn't be necessary for most
MSX-1's, I had absolutely NOOO problems with it, running programs on
this MSX-1 was 'business as usual'. I even had a memory mapper in
there once, after a first initialisation 'by hand' (MSX-1 BIOS
routines don't do THIS, but otherwise MSX-1 and memory mappers are no
problem either), several 'MSX-2 only' MegaROM cracks (Nemesis and
such, originally MSX-1 as you will know) ran fine, even in a sub-slot
(and no, this was not the first sub-slot only, or the last, but slot
3-2, as in the Philips MSX-2 models).
Besides:
This RAM-file cartridge that started all this, must be something like
a 'stand-alone disk-driver', that more a less works just like a
separate disk-interface, so I'm sure this guy CAN simply boot to
BASIC, and read out the ROM by software.
Apart from that:
If you DO want to insert a cartridge in a running MSX, there's a
safer way to do it: hook up a switch between +5 V and the slot-select
signal of the slot you want to disable, then, when booting the
machine, switch it on shortly, just after the MSX-logo appeared (when
slots are searched), which short-circuits the particular slot-select
signal with +5 V, making it 'high' (inactive), and thus disabling
this slot, for as long as you keep the switch on.
Absolutely worst thing that can happen if you do it this way, is
destructing a slot-select signal output of some custom IC (S-3527
MSX-engine for instance), which would make this particular
cartridge-slot useless.
In practice, you would probably have to short-circuit it for a long
time (minutes, hours) to do so, and in fact I doubt it would ever
happen (if only 1 output is short-circuited, for most IC's this means
no more than handling the excessive heat-production caused by the
short-circuit current of this 1 output, making it 'peanuts' for many
IC's).
All clear now?
Greetings,
Alwin Henseler ([EMAIL PROTECTED])
http://www.twente.nl/~cce/index.htm (computerclub Enschede)
http://huizen.dds.nl/~alwinh/msx
(yep, some MSX-pages of my own have appeared, I called it 'the MSX
Tech Doc page', a bit empty now, just my MSX Super Turbo circuit, and
a home-built cartridge-loader (check it out if you could use one!),
but more will come...in time....)
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