What do each of the 256 I/O registers do, bit by bit?

[StinkerB06]

The documentation doesn't show what all of the I/O registers do. I know some, like the AY-3 sound interface, but what about the others?

[indigodarkwolf]

There is no AY-3 sound interface. Do you mean the YM2151?

[StinkerB06]

I thought there were AY-3's because of this:
https://murray2.com/threads/commander-x16-update-from-david-on-facebook.183/

[indigodarkwolf]

A YM2151/SAA1099 combo is currently the favored design, but nothing is final.

As for the other I/O ports, the documentation clearly indicates that most are reserved for future expansion. As in, they are currently unassigned and do nothing. Is there a specific feature you're asking about?

[StinkerB06]

The old design had two 8-bit DACs for stereo PCM sound, that I assume were controlled via one of the 8-bit GPIO ports on each AY chip. Will these DACs be in the final design?

[PeterCamilleri]

By the same token, there seem to be very few details on the Real Time Clock. Perhaps a part number could be revealed?

[mist64]

@PeterCamilleri To the best of my knowledge, no decision has been made on the RTC, and it seems to be an optional part.

[PeterCamilleri]

@mist64 That makes sense. A quick check reveals that parallel interface RTC chips are both old and expensive. Perhaps a better idea would be to add an I2C interface. This would allow the use of inexpensive I2C RTC chips as well as expansion to the army of I2C chips on the market. The I2C interface could be assisted with some jelly bean logic, or another VIA, or simply added to the VERA FPGA as a (small) peripheral macro device.