Here are my thoughts on a few of these issues.
Construction Techniques:
A little off the topic, but sorry Pete, I like a lot of your ideas but wirewrap isn't one of them. I'll take point-to-point soldering any day.
65816 vs. 6502:
I sort of asked for trouble when I put that "65816 daughterboard" comment in the initial specs for the board on the
www.6502.org site. I did this because I knew that someone would ask for it. I don't think it is of general interest to put the 65816 on the board itself. It's a *much* harder chip to find and more difficult for beginners to work with. I say let's consider making a 65816 board later (after the 65C134 board <grin>). Or, with the expandability we're designing into the address decoding and bus connectors, you can leave the 6502 off of this board add a 65816 easily on a separate card. Of course, if the majority feels differently about this matter we could put the 65816 in instead. It doesn't seem right to me at this stage though.
Address Decoding:
I really like Pete's ideas about the address decoding and expansion connnectors. The decoding into 8K blocks with one block divided into 1K segments for I/O makes a lot of sense. With three I/O devices on the card (two 65C22s and the 16550) that leaves five decoded I/O selects to stick on the expansion connector for easy expandability. And with the chip selects for every chip going into a jumper block the address decoding has unlimited expansion potential. We need to look at these existing busses (RM-65, CS/A) and start making some preliminary bus pinouts.
Clock Crystal vs. Oscillator:
Chris Ward suggested the jumper-selectable clock frequencies and I like the idea a lot. It's nice for experimenting, especially in a classroom setting. How about we have holes for the regular crystal and also for a dividable oscillator circuit? Considering the size of the board already (four forty-pin chips) it won't add much if anything to the footprint.
High Speed Operation:
I originally wanted a super high speed board myself, and so far there is nothing in the design that limits your potential speed other than the parts you plug into the sockets. The 65C22 is available up to at least 8 MHz. I'm sure the 16550 is available in that speed and higher.
Anything I forgot? Comments, suggestions?