>Hi people,
>
>Thinking that you should set the interruptvector at #C000 when you set I to
>#C0 is a commonly made mistake in the MSX world. You should set your
>interruptpointer at address #C0FF instead. As some of you might know, the
>databus in the MSX is connected to VCC with pull-up resistors. As a
>consequence the Z80 will always fetch the value 0xFF when reading from the
>databus at a moment that no device is writing to the databus. For example,
>when the Z80 reads the databus in IM2 after having received an interrupt
>request.
Well as I wrote I always filled in the whole area from #C000 to #CFFF so I
never got problems with it (nowadays I program under Dos environment so I
don't use it anymore). By the way, that will be C0FE and not C0FF, because
interrupt-vectors can only be even numbers, bit 0 is ignored (always zero).
Recently, I read the specs of of my Philips modem adapted to an RS232... The
chip inside can generate an interrupt-vector... Is this put through to the
MSX, will it really generate a vector when used in IM2??? If so, that would
be cool. Or is the MSX standard not capable to use a IM2-vector?
~Grauw
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