here's a little info, i'd try to run down the info on the PrimeTime II IC and the SWIM II floppy disk controller capabilities before doing anything else. the LC was the last machine i can think of offhand with two FDD's implemented but maybe one of the powerbooks or something else used the SWIM II and could do dual floppies, dunno.

quoted from developer's note:

quote:

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PrimeTime II IC

The PrimeTime II IC supports the I/O bus. It combines functions performed by several ICs in previous Macintosh designs. The PrimeTime II IC includes

• data bus buffers for the internal I/O bus

• address decoding for I/O devices

• dynamic bus sizing and data routing for the I/O bus
• interface adapters VIA1 and VIA2

• interrupt controls

• a SWIM II floppy disk controller

• sound control logic and buffers

The PrimeTime II IC serves as a bridge between the system bus and the I/O bus.

The PrimeTime II IC provides the data bus features of the MC68030 that the MC68040 does not provide. Those features are byte steering, which allows 8-bit and 16-bit devices to be connected to a fixed byte lane, and dynamic bus sizing, which allows software to read and write longwords to 8-bit and 16-bit devices. Those features allow the computer to work with existing I/O software designed for the MC68030.

The PrimeTime II IC also contains the sound control logic and the sound input and output buffers. There are three separate buffers—one for sound input and two for stereo sound output—so the computer can record sound input and process sound output simultaneously.

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jt ™.
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