The ELF alternatives -------------------- Feb 5, 2005 rileym65 wrote: > Do you mean my tiny elf design? the Pico/Elf is a bit larger, > it is the same size as the Micro/Elf board. We've discussed so many versions that I'm not sure. I don't remember hearing about a "Tiny Elf"; only the Pico/Elf and Micro/Elf. I thought the Micro/Elf was sold out, and the Pico/Elf was its replacement that you are working on now. Is the Tiny Elf a third version? > I would certainly have no problem increasing the board size a > bit to space the parts out... so many people were talking about > ultra-compact designs, so that is what I tried to do. I think different people are looking for different things, so no one design will satisfy them all. I now think that rather than a one "compromise" design, it may be better to have several different designs. People can then choose whichever one they want. 1. The original PopTronics Elf Your Micro/Elf and the STG Elf2000 are great models of this as-is. The Elf2000 looks better for someone who wants to add the 1861. Your Micro/Elf has the extra address displays, and is smaller than the original Elf. Both support bigger memory, and can easily run Tiny BASIC etc. without extra boards. 2. Higher-end; RCA VIP / Quest Elf / Netronics Super-Elf These added mass storage, video, hex keypads, memory, expansion slots, etc. But they dropped the simplicity of the toggle switches and ROM-less operation. The Elf2000 does some of this, and it sounds like your Pico/Elf was moving in that direction with its IDE interface. 3. Lower-end This is what I was thinking of with my "membership card" idea. Something even simpler and cheaper than the original Elf. Something good for a beginner who wants to get familiar with the 1802 without spending a lot of time or money. Also, I wanted to make it *very* low power, for solar-powered robots and other micropower applications. Mike, is your "tiny Elf" intended to address this market? It sounds like that's the case. If so, I think you are doing a great job. I'd suggest sticking with it... drop the low-power requirement (since it doesn't matter to most people) and concentrate on a very low-cost, very simple design. I'd make the board a little bigger, with the parts more spread out, good labelling, marked test points, etc. so it is easier to build and fool around with. As we've said, use sockets with DIP switches as the input switches. If the builder wants, he can easily add his own toggle switches. Same for the display; I'll bet the board can be laid out so you can install either a latch and 8 LEDs, or two TIL311's. On power: If the CY7C199 RAM has a low power consumption when its /CE is high, you might be able to design the circuit so /CE only goes low during TPB high. This way it is only active for 1/8th of each 1802 cycle, which might cut power consumption 8:1. The CY7C199 is so fast that this still allows *plenty* of access time. > in fact, if we add to the size a bit, we can either add the 8 bit > latch for the upper addresses, or use dip switches for them to > allow multiple programs This is fine, but beware of engineer disease! It is hard to resist adding "just one more feature..." But the cost and complexity keep going up. Save the expansions for your next Micro/Elf. My priorities would be to make it 1) as cheap as possible, 2) as simple as possible, 3) do as much as possible with the parts that you have. In that order! For example, I needed a 4013 to make the Load mode work. The second half was unused, so I used it to latch A8. This would allow 512 bytes of RAM instead of 256 bytes with your CY7C199 for "free". But I wouldn't add the extra chip to latch more address bits. -- Feb 5, 2005 craigsherenow wrote: > I know that there are a few people selling elf kits but all or most > of them break the $100 or higher. What if one of the tech savvy > people in the group could sell a kit with a plain perf board, all > the chips and a easy to read plans to put together and this would > leave the buyer what the opt of using sockets or not Hi Craig, You can already download the plans for building the original Popular Electronics Elf, and all the parts (except the 1802 itself) can be ordered from suppliers like Jameco (www.jameco.com). The 1802's are currently available from several sources for $10 or less. The whole thing will certainly cost under $50. The difficulty of actually wiring it up is what stops most people. That's why we have several people offering PC board Elfs. But due to "engineer disease" (the malady that causes engineers to keep adding features forever), these kits are all significantly more powerful (and thus more expensive) than the original Elf. It was posts like yours that inspired us to start brainstorming a "membership card"; something that truly *is* very simple to build and very inexpensive! Keep reading -- chime in with comments like you have been, and we'll see what we can do!