OT-ish: Build-it stuff

Microcontrollers, PALs/GAls, CPLDs. All come with the security fuse blown. Obviously EPROMs are readable :-) In a few cases, they make the object (binary) file available to program your own device, but not the source. Which is not particularly helpful. Yes, I am well aware there are ways to reverse-engineer some of these devices, but I have to weigh up the effort to do that against the effort to design the whole thing from scratch (and have it just the way I want it). Exactly. Rarely does the published design exactly meet my needs, I want to modify it. And that may mean modifying the firmware too. I don't expect them to support all my old machines, but I wish they'd let _me_ do so by documentign the interface properly. If a device plugs into a serial port and uses the Tx and Rx line conventionally, then I'd like to know what commands I can send the device, and how it responds. Or alternatively, give me the source to the firmware and/or the PC program and I'll work it out. I've heard economic arguments (mostly as a reason for not homebrewing) many times before, and I don't believe it's the whole story... Let me go off at a tangent for a moment. All my life I've been interested in clocks, and one day I intend to make a real mechanical clock. I'll have to get a lot better at machining first, but I still want to do it. Economically, this makes no sense at all. To make a clock from scratch probably needs \pounds 5000 to \pounds 10000 worth of tools (many of which i have, it's true, but I'd still need to get gear cutters, etc and they're not cheap). The metal to make said clock is around \pounds 100. And the result is a much worse timekeeper than a 5 quid quartz clock from the local household shop. But I still want to do it, to learn, and to have the enjoyment of making it. And it appears others do likewise. There's at least one magazine which has an article every month on desinging/making a clock (and other articles on making parts as part of antique clock restoration). There are many books and plans for homebuilt clocks. So I can't be alone in wanting to do this. Now lets get back to computers. The difference in performance between a homemade mechanical clock and a quartz clock is probably comparable to the difference in performance between a modern PC and a homebuilt processor. The tools needed to make a homebuilt processor are cheaper than those needed to make a clock, thouygh. And yet, I've not seen one book or magazine article on making a processor from scratch in the last 10 years. If some people think it's worth making a clock from scratch, why not a processor. I will end with a wuote from a book entitled 'Every Boy his own Mechanic', published about 90 years ago. It's the start of a chapter on a home-made telephone system ' For some years previous to 1914 the constructive instinct and ability inherent in many of us was almost snuffed out because most of the mechanical and electrical things we wished to possess were so cheap that they could be bought ready made. Often the prices quoted were actually below the cost to us of the raw materials, and so we came to think that constructive hobbies were a bit futile. Lots of those cheap things were amazingly good, but some where exasperatingly bad, and the bulk indifferent. Still, we bought the stuff, learned nothing from it, and clean missed all the solid satisfaction that lives for ever in building and contriving and creating Take the ready-made cheap telephone, for instance. How long did it take to get fed up with ringing and asking "are you there ?" Was it really worth the outlay of 15s to 45s? Frankly, no. Why? Because our purchase locked us out from all the subtle mysteries of an ever-wonderful instrument (simple though it may be), and we had been robbed of all the joy of its making. If it failed to act we discovered that we could not put it right. If it acted perfectly, we took the whole thing for granted and soon became bored. But to build up that same installation oneself in the face of difficulties from the homeliest of raw materials, and at last to have it (in litteral fact) voicing our triumph in our eager-listening ears - ah, that is a very different matter!' And that is exactly how I feel about homebrewing electronic devices now. -tony