At 04:43 16/01/2004 -0500, der Mouse wrote: I remember building a LED matrix as a project when I was an apprentice (for Ferranti Computer Systmes). 8x7 LEDs, driven by the 8-bit parallel user-port on a BBC B. Made some nifty patterns, as well as scrolling text, etc. I still have it, but not sure I can find my software now. Anyway, a quick google turned up a mfr that does LED matrix modules. This one looks close to your dpi requirement http://www.okaya.com/HP3/image/RG160160-C.pdf (if I am translating 160 dots in a 63.5mm wide module correctly) you might have to deal with the 'margin' though. But I am sure if I find a hit that quick, there will be others about. Rob

[Multi-reply here. Second-level quotes are me.] ["Rob O'Donnell" <classiccmp.org(a)irrelevant.fsnet.co.uk>] 64dpi, yes, that's encouraging. [Pete Turnbull <pete(a)dunnington.u-net.com>] Yes...I have a feeling it'd have to be entirely custom. (It probably would anyway, given what I want to do with it. See below.) Ouch. And that's only 10dpi one way by 20dpi the other. On the other hand, those LEDs are probably intended to produce enough light for a relatively large viewing area. My plan calls for a very low total viewing area attributed to each LED. Efficiency doesn't much matter. If it's sucking 500 watts, it's dumping 500 watts, and whether that comes out as heat or light makes relatively little difference - except for what little escapes into space, it all ends up as heat. Maybe. See below. [Brad Parker <brad(a)heeltoe.com>] Well, given what I want to do, interconnect is one of the issues, but I believe it should be fixable.. I suspect the panels you describe are probably at very coarse resolution, probably no finer than maybe 4dpi - most consumers of large panels don't also want fine resolution. What I really want to build, y'see, is a cellular automaton machine. Ideally, it would be little modules that abut one another and communicate neighbour cell state between modules somehow. Then add a little logic behind each LED, and clock them in parallel. Power distribution is one issue that would need attention. I believe clock distribution actually isn't much of an issue, because they don't need to be truly clocked in parallel; provided you do something like sample neighbour state on the rising edge and change state on the falling edge, clock skew across the array doesn't matter as long as there's little to no clock skew between adjacent cells. Add a few control signals and a little more logic, and you need a host interface at only one point (it wouldn't be used in normal operation anyway). Signals that go to the whole array (like control signals and clock) could be regenerated by each module, to eliminate the need for central drivers capable of driving thousands of loads. This means that no individiual pixel needs to generate much light - certainly nothing like as much as most single LEDs produce. Taken in aggregate, a square foot should be capable of (very roughly) as much light as a square foot of those panels Brad Parker mentions, and should produce no more than about as much heat, certainly not hectowatts per square foot. I don't know whether it's feasible to fabricate LEDs on the same wafer as logic gates, but if possible that seems like a promising approach to me. I'm quite sure the technology is up to it; even ten thousand cells per square inch (100dpi) is nothing, not even if you go overboard with generality and give each module 512 bits of RAM to hold the automaton definition (I would be willing to live with limiting myself to a 3x3 neighbourhood). Communication between adjacent modules would need to be worked out, but that problem I feel sure can be solved. Physical alignment is just a question of packaging. That leaves only the money. I'm certain this wouldn't be cheap. :( Ah well, but that our dreams should exceed our grasp, or what's a heaven for? (Maybe not quite what Browning wrote, but more or less the same sentiment.) /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

Snip Wait for large format OLED. Just begun with small devices this year, last year was one or two that featured OLED. Cheers, Wizard