At 03:04 PM 03/06/99 +0100, you wrote:
>> What about the inter slot call? That's one RST you'd better not redefine.
>> For example, the H_KEYI handler in the NMS8250 uses it.
>
>AAAAARGH! That is bad... Well, I'll just make sure BIOS is switched in
>page 0 when I call it. That doesn't happen very often anyway, only when I
>want to stop the diskdrive.
Reading from disk may also need an inter slot call (if your machine
contains more than 1 diskROM, for example when you use DOS2).
One tip for when you enable the BIOS only when accessing disks: make sure
that if DOS2 is present, you call "invalidate disk buffers" before you load.
Disk buffers are a kind of cache. It is automatically invalidated after a
certain time (less time than any human takes to swap a disk). But if you no
longer call the normal interrupt handler, time "freezes" for it. So DOS2
will always think the disk buffers are valid, even though it's possible the
disk has been changed in the time its interrupt handler wasn't called. You
can solve that problem by always invalidating disk buffers when you start a
series of loads.
Bye,
Maarten
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