One final comment on all the updated interface card ideas...
The problem with NuBus cards is that the maximum theoretical performance of a NuBus card is 10MHz X 4 bytes = 40 MB/s. And the reality is quite a bit slower with bus overhead. For example, on the NuBus, the data and address pins are multiplexed, which means that addresses and data are transmitted on teh same wires, sequentially. A PDS bus has separate address and data busses as well as running faster than 10 MHz.
Apple's guidelines for cards for PDS slots are very similar to NuBus cards, so there's actually not that much difference in developing one or the other.
With FPGAs it's not that difficult to build a card which will work regardless of which PDS slot it's plugged into. Although making it autodetect that might be a bit of a trick. It'd be nicer if the user set a jumper.
Of course, there's only one PDS slot in each machine. So a multi-function card such as IDE/USB mentioned above becomes attractive.
At this point one starts thinking about all the things that would benefit from faster performance and is quickly contemplating a card wtih IDE, USB, video, and 10/100 ethernet all rolled into one. Then, if one assumes that a machine wtih such a card installed would also be one with a fast CPU upgrade, one starts thinking, "hey, the upgrade is running at 40 or 50 MHz, why am I limiting my peripheral upgrades with a 16 MHz bus speed? If I put them all on the same card, they could all run at 40 or 50 MHz bus speeds.
And then one start comptemplating a total 68K computer upgrade that just uses the host motherboard as an I/O interface....
The problem with NuBus cards is that the maximum theoretical performance of a NuBus card is 10MHz X 4 bytes = 40 MB/s. And the reality is quite a bit slower with bus overhead. For example, on the NuBus, the data and address pins are multiplexed, which means that addresses and data are transmitted on teh same wires, sequentially. A PDS bus has separate address and data busses as well as running faster than 10 MHz.
Apple's guidelines for cards for PDS slots are very similar to NuBus cards, so there's actually not that much difference in developing one or the other.
With FPGAs it's not that difficult to build a card which will work regardless of which PDS slot it's plugged into. Although making it autodetect that might be a bit of a trick. It'd be nicer if the user set a jumper.
Of course, there's only one PDS slot in each machine. So a multi-function card such as IDE/USB mentioned above becomes attractive.
At this point one starts thinking about all the things that would benefit from faster performance and is quickly contemplating a card wtih IDE, USB, video, and 10/100 ethernet all rolled into one. Then, if one assumes that a machine wtih such a card installed would also be one with a fast CPU upgrade, one starts thinking, "hey, the upgrade is running at 40 or 50 MHz, why am I limiting my peripheral upgrades with a 16 MHz bus speed? If I put them all on the same card, they could all run at 40 or 50 MHz bus speeds.
And then one start comptemplating a total 68K computer upgrade that just uses the host motherboard as an I/O interface....