cpld pcb eagle
Hi,
I just built a CPLD dev board, mainly to use up bits'n'bobs laying around. My advice, (and the advice others have given me) is to keep it simple. It's easy to keep adding things like LCD, PS/2 port etc.. but start with what the chip needs.
Stable power supply, that can deliver enough current, a versitile clock (maybe a socket for crystal oscillators) and most importantly, access to every I/O pin. And, of course, a programming header (or have the DL cables buffer circuit, on board, with a DB25 port on it, if you've got the space). Some extra's are pull-up resistors, and maybe a buffer or two.
You may not need to use all pins in a project, and you can tell the chip which pins you want to use for what, but it allows you to connect external boards to it. For example, say, for some reason you want to connect an ADC to it. Theres no point in sticking it on your development board if you don't use it much, but you could have a seperate board which all your 'bells and wistles'.
Theres nothing worse than building it and realising you need to use more pins than you've made available. Heres a small picture of mine (made with eagle 3D).
Good luck
BuriedCode.