This project is a homebrew computer based on the Motorola 68000 CPU. Design includes four megabytes of RAM, 128kB of ROM, Something for video, two serial ports at 9600 baud, and eventually networking and a hard disk.
The purpose of this computer is two-fold: To show it's really not much harder to build a 16-bit homebrew computer than it is to build an 8-bit homebrew computer, and to build a server for Hackaday's retro site.
It's sad to see that your abandoning the backplane.
I was watching this closely as I like the old modular systems that plug into the bus.
Well, I did buy all the connectors (50 pin dual row 0.1" headers) so I guess I now have to extract the digit and do something myself.
I totally agree about mixing old 5 Volt chips with 3v3 CPLD. I built a Compact Flash inteface (IDE) for my Amstrad CPC 6128 using CF / level translators and a 3v3 CPLD and it didn't work because the noise margin was too low for the CF cards Vih of 4.8V - perhaps I should put it up and submit it as a fail lol. I may give it another go as the CF should work at 3v3 instead of 5v.
All was not lost though because the interface was IDE so I plugged in a 2.5" hard drive and it work perfectly even though I was looking for more *removable* media. So that proves that a 5 Volt Tolerant - actual 3v3 CPLD will work with *standard* 5 Volt TTL chips with LVTTL.
Anyway the CPLD's that I have successfully got working with 5 Volt TTL are Xilinx XC9536XL / XC9572XL and Altera EPM240 / EPM570. I bought a 100 XC9536XL's so that will keep me going for a while. The Altera's mentioned have a k or so of serial FLASH as well.