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Showing results for tags 'expansion cards'.
I looked on Mouser for an ISA slot connector. I found a whole backplane ?? for $28+. I looked other places. Briefly. I found nothing. Looking on Mouser for a PCIexpress connector, however immediately gave me this: PCI Express / PCI Connectors 98P CARD EDGE ASSM VERTICAL A 98 place socket for $0.78 quantity 1, $53.40 for 100. A common, inexpensive part. Nice. I suggest that the PCIexpress (x8) connector would be more appropriate for Commander X16, just based on availability. 98 pins may seem like a lot for an 8/16 data bus, but: The 65C816 has a 24 bit address space. For EMC and signal integrity reasons, every signal should have a return path (ground). Adding a dedicated return for every signal will make the bus much quieter. If we were to expose all 38 signal pins from the 65C816, plus the extra de-multiplexed 8 address bits, and then give every signal a ground, that leaves just four pins for Vcc. That doesn't seem all that extravagant to me. I'm not saying we should directly expose the full CPU bus, but having room to choose what we want to share is A Good Thing(tm). Any (weak) argument that this would tempt people to insert PCI express cards would also apply to ISA connectors. You can just reverse the socket or change the distance from the edge of the motherboard so a normal PCIe card would not even fit. I'm not suggesting that we support PCIexpress, just that we use the same mechanical connector because it is cheap and readily available.
I want to design an expansion card, but I haven't found any schematics or other info I would need for the interface. I understand that this may not be stable right now, but I would at least like an idea of what it might eventually look like. I see four slots on the prototype motherboard. There must be a pinout somewhere.
In talking about changing the card pins in this thread , I wonder if there could be a solve for being able to mix audio in some way. There's multiple folks thinking about sound cards. I myself will be pretty over the moon with the native solution available in the X16. Nonetheless, while I was thinking about sound card examples, I thought about something like a GUS solution (which, to refresh memories, it was a sound card that has it's own RAM and had hardware accelerated sample playback). In that context, an application would just tell the card to play sample X (optionally at frequency or note Y). Anyways point is, whatever sound cards folks come up with, the issue of how to mix the audio comes up. On the MB6582 (the 8-SID monster MidiBox), there's a passive mixer that mixes all 8 sids into a single stereo output. That design is a bit attenuated but it works and seems inexpensive (assuming there is space on the board for a few resistors and traces). Wondering if perhaps using 2 pins on the card slots for stereo audio would be nice? Although a cheaper solution might be to just have an "external audio" pin header on the board (which one could optionally jumper to ground to avoid noise), kind of like the CD audio connectors of yore. Ramblings aside, having a means to mix audio from sound cards with the internal audio of the computer would be a nice to have. Certainly not a need to have but could avoid user headaches and enable musicians and app devs alike to get the most use of all the hardware without having to require any external mixers and things. Given the X16 itself, as of the current proposal, will have 26 channels total (16 PSG, 8 FM, 2 DPCM) - the need for external sound solutions is perhaps lessened to a degree, but while I'm all about the chiptunes, I have a feeling the draw for an efficient DPCM card/sampler will be compelling for some. Plus the folks that really want a true SID sound, etc.