Kai, you say,
"What works for a professional of many years of experience does not necessarily work for a beginner."

and I have to ask, "Why not?" If it's done correctly it will work the same.

The OP is not proposing to use the latest technology, but, rather, the technology of the late 70's, where signal propagations were less than 10% of the gate delay, and clock periods were typically 10 or more gate delays. He's not proposing to use the fastest available technology and he's proposing to use technology that was "mature" back in the '70's. I don't approve of what he's wanting to do for a number of reasons already stated, but if he does it in wire-wrap, at least he won't waste a bunch of money on a circuit board.

2. What worked successfully in the 70' need not necessarily to work today. Take care, todays microcontrollers and digital chip families are much much faster than in the old days. Transition times of output signals is what counts here, not so much the clock frequency of micro.

to which I'd respond, that there's no reason to believe that either. First of all, the OP's not proposing to use today's technology, and secondly, if he uses a proper wire-wrap board, every trace will be as short as it can possibly be, and at a consistent distance above a low-impedance ground plane.

Now, some people don't use shortest-distance routing, but that's their problem, not mine. Ground bounce is easily minimized by connecting each device pin directly to the low-impedance supply or ground plane, and providing a low-value (~220 pF) bypass member at each supply or gnd connection. Swamping capacitors can be located throughout the board in whatever locations are practical. Back when VME was new, the sales rep's from Signetics and Motorola both recommended their customers buy my boards rather than theirs in order to avail themselves of the better bypassing ability, and the low-impedance supply/gnd planes. They were, then, building digital circuits with clocks over 100 MHz without any problems.

Like most any one else, he can buy a ground/power plane wirewrap board. If he hasn't, in this poorly thought-out application it won't matter because it counts barely as fast as he can do it on his fingers.


you go on,"3. You talk about "never having had problems, that could'nt be worked out". So, you epxerienced problems from time to time?"

to which I reply,
Yes I've had problems, e.g. cold-flow of insulation, wires broken within the insulation, poor solder joints at the supply pins, and, more often, misplaced wires or incorrect logic, clock phase, etc. Aside from the cold-flow, those same problems arise in circuit boards, except that you can easily fix them in a wire-wrapped design at a cost of aobut $0.05US. If you have boards made, you generally have to spend a lot more money, which is clearly a problem for a beginner. If he wires something wrong, he can easily fix it. If he has to change the logic, he can easily fix it. If a particular component doesn't work, he can fix that too. It's not so easy with a PCB. Once he has a working circuit, trivial, though not particularly practical or desirable, in the case he suggests, if he still thinks he wants to spend money on a PCB, he can do that, having convinced himself that it's worth the time, effort, and investment. Digital circuit design, at this level, is trivial. What's more, it's non-critical. Unless he does something foolish, or fails to read a datasheet, he'll have a circuit that works within a half day of when he starts. I'd certianly fire anyone who didn't, and I'd not give them much credit for the choices made in the design.

RE