Thanks to everyone for their input. Please keep them coming because I still haven't decided.

1. I like the idea of using some of those cheap devkits instead of my own SBC. There's no way I can compete with a $100 devkit in terms of price. So using a devkit could make it that much more likely that a reader could buy one and use it. It does, of course, pretty much preclude them from actually building one themselves.

2. I have long thought about getting rid of the EPROM socket. I'd be willing to wager that of all the SBCs built and sold, probably no-one is using the EPROM. So perhaps that's all the justification I should need to get rid of it. It did, however, help illustrate the difference between MOVC and MOVX and the function of PSEN as compared to WR/RD. Even if no-one used it, actually seeing the physically separate socket helps illustrate the reason for the different lines and instructions.

3. I have also thought about going with a higher capacity SRAM IC but I haven't investigated whether they are any more available in DIP than the 32k SRAMs. Even if they are, how much time does that buy me? Are they going to disappear in another year or two, too?

4. I like Jan's idea of making all kinds of things possible in a DIP32 socket and controlled by jumpers. That would give neat flexibility. The only thing I'm concerned about is turning a straight-forward design into a schematic nightmare that a newbie would go crazy trying to figure out.

5. I rather like the Dallas 89C4x0 parts because they have the serial-based ISP which avoids a lot of headaches with the Atmel parts.

Regards,
Craig Steiner
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