| Electronics > Projects, Designs, and Technical Stuff |
| Z80 Single (Perf)Board Computer |
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| obiwanjacobi:
That is pretty tight. Are you sure you will be able to connect it all? Other than that, very nice. :-+ |
| grumpydoc:
--- Quote from: obiwanjacobi on April 02, 2017, 05:53:35 am ---That is pretty tight. Are you sure you will be able to connect it all? Other than that, very nice. :-+ --- End quote --- Yes, every time I look at the board and the drawing 100x160mm starts to look very small :) I've managed this sort of density on perfboard before but this is definitely the most complex that I have tried. In fact this is exactly why I have taken the trouble to draw the layout rather than just wing it from a schematic - or occasionally just make it all up as I go along. I think power and decoupling will be the challenge, the intent is to route most of the power on the top of the board with reasonably sturdy hook-up. I have some 22AWG stuff that I can use, at 1.2mm external diameter I can get two strands between the rows of IC's; the slight undercut of a turned pin socket helps here. If that does prove too chunky I have some 30AWG wire wrap wire, that might be slightly thin for power but I'm only anticipating the board drawing half an amp or so. I did consider using sockets which incorporate decoupling but those are a bit on the expensive side. I have some 32 pin sockets with built in caps (for the SRAM) but they are a different style so I'm 50/50 on using them. After that I have some 0.2mm (32AWG approx) and 0.315 (about 28AWG) "self-fluxing" wire - I'm not sure what the coating is but similar to this stuff. I bought the reels years ago and, despite a good few projects, still have miles of it left. The nice thing is that you can take a length and run it along all the points that a given signal needs to connect to and then solder them all in one go. A dab of superglue helps keep longer runs neat and I could probably do this board and not have the wiring be above the IC socket pins on the back of the board. |
| grumpydoc:
--- Quote from: wilfred on April 02, 2017, 11:35:03 am ---I hope you don't end up with so much tightly bunched up wire that it just gets in the way and/or makes repair or modification difficult. Why can't you get a larger board and make life easier? If it is because you already have it, I get that. --- End quote --- Yes, it's pretty much because I happened to have it, but also because it's quite a nice size for the project. For rework the wire can just be cut off by the pin and a new one laid. |
| obiwanjacobi:
Small decoupling caps (100n) should fit inside / under DIP IC sockets. Perhaps you could take the single-step circuit and put it on a separate small board and plug it in only when you need to debug? You just need a small header for it to connect to. That may free up a couple of ICs worth of space. |
| danmcb:
haha, respect! you must like pain though ;-) I would wire wrap this myself - if I *had* to do it this way. Or, honestly - maybe just go straight to PCB and save an absolute crap load of time (only to spend it on something else after of course). You could use free diptrace and modularise it maybe? I didn't study the design, but core CPU and memory on one card, then a ribbon to an IO card maybe? it would save you a world of pain, donny. |
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