+1 on the cheap scope recommendation. Without seeing your signals, solving a problem with shoving bits around is (educated) guesswork. Nothing like struggling f

+1 on the cheap scope recommendation. Without seeing your signals, solving a problem with shoving bits around is (educated) guesswork. Nothing like struggling for days with a weird fault or corrupted xmit only to throw a scope on a bus line and see in a few seconds where the problem lies. (voice of experience speaking). And here's the good part: These days, a basic scope is incredibly cheap! Check ebay and/or amazon for a DSO138. It's a simple creature but ideal for a project such as a Z80. There are two variants of the DSO138 - kit form and pre-assembled. Prices are an astounding $25/$30 respectively. Unless you just want to spend 4 hours soldering (not a bad thing), spend the extra $5 and get the prebuilt. And make sure it has the latest firmware (cleaned up some bugs, improved centering, and reduced noise). And @mindcrime - please blog that project! I know I speak for loads of others when I say I'd love to watch your progress. I never get tired of seeing others do cool stuff I don't have time for anymore. :)