(1500 words, sorry) Dave Long writes: > What about handsets? Are phone companies not as profligate with those > in places where they don't expect to quickly make it back on the bill?
Cell phone handsets? Mine cost $38 in Quito, and apparently it's locked to the carrier! I'm surprised they can get away with that (and in particular not telling me when they sold it to me) but perhaps it shouldn't surprise me. Most Ecuadoreans don't seem to have cell phone handsets, and only a third of the world's population does. So I think there's room at the bottom for cheaper communication devices. (The other problem with handsets, of course, is that the politics of control embedded in their design are diametrically opposite to what I want to promote. In a sense, handsets are The Enemy.) > (It's clear that a handset is certainly powerful enough to self-host[0] > -- but do we have any current examples?) Not at the low end, although you can run Pippy or some Schemes on the Treos, and Symbian Python on the Symbian phones. So far I don't know of any phones that can compile their own operating systems. > Assuming that it is worthwhile to spec a device much less powerful than > a low-end handset, and guesstimating wildly on no experience: (so what > massive errors am I committing, infra?) > > 1/ How much do batteries cost in Ecuador? Does it make sense to > attempt to hit a price point that'd be only a few multiples of the > upkeep cost? As I think I commented in http://courageous.murch-sitaker.org/~kragen/electronics/game/index.html I have found "counterfeit" AA and AAA batteries for 15 cents. They work as batteries, but they're awfully light, and I suspect they won't last long. Brand-name AA and AAA batteries can cost 50 cents to a dollar each. It's not necessarily an upkeep cost. As I said in http://courageous.murch-sitaker.org/~kragen/electronics/goodcalculator/index.html the nice calculator claims to last 17000 hours if it's continuously flashing the cursor. That's 23 months. Finally (I sound like a lawyer: my client didn't do X, also X is legal, and if it were illegal the plaintiff wouldn't have standing to sue) I suspect that people's discount rate for cash expenditures is higher in poorer countries, perhaps due to a lack of credit; this might explain the prevalence of Duvvacell and SQMY batteries in the informal economy here. > 2/ As a quick double check, here's what I see for parts from a > same-day/next-day distributor: (attempting a networkable > Sinclair-style kit based partly on Kragen's list of dissected consumer > electronics) > > microcontroller AVR w/ 1K RAM 5-10 CHF > lcd display 3x16 w/ chargen 25 CHF [1] > membrane keyboard 25 CHF > power + IR networking + glue 5+ CHF > ----- > 60-70 CHF > > Figuring prices to be around half that in USD from DigiKey or the like, > and guessing that factors of two from quantity price breaks and the > necessary markup back to a retail product very roughly cancel, that > could easily be a bit high. Do you mean e.g. the LCD should cost US$12.50 and the microcontroller US$2.50 to US$5? Digi-Key has fairly nice low-pin-count AVRs from just over US$1, and they have LPC2101s (60MHz 32-bit ARM7TDMIs, 2K RAM) just under US$2. I never did find an LCD at a reasonable price from them, but apparently you can buy them (inconveniently wrapped in nice calculators, but with a keyboard as a bonus) in shops in Ecuador for $4. I don't have any idea what membrane keyboards cost, but I don't imagine it can be too much more than the calculator keyboards in the $4 and $7 calculators I bought, or the 9-key keyboard on the $2.40 game. In fact, I thought membrane keyboards were supposed to be rock-bottom cheap. One of the nice things about AVRs is that you really don't need any glue circuitry. You can just hook a couple of AA or AAA batteries, or a lithium button cell, up to the power and ground pins, and the thing boots. You can even reprogram it in-circuit at the cost of a few pins. IR networking costs an IR LED, two CPU pins, and a current-limiting resistor; the discrete components there are under a dime. > How about using a 2nd mcu to drive an external TV display, and somehow > magically Wozzing out on the support circuitry? Back in March, I linked to several projects in my "TV output on low-cost portable computers" kragen-tol post that drive TV with a microcontroller. In case the links are still valid, here they are: Texas Instruments' "application report" SLA1177 (http://focus.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=slaa177&fileType=pdf) reports on using ... the MSP430F1121A) to generate 32-pixel-wide NTSC video signals in real time. Digi-Key tells me that this microcontroller model costs US$2.13 in quantity, and apparently it's clocked at 8MHz without a clock crystal... Someone at Cornell is using an ATMEGA32 Atmel AVR to generate 128x100 pixel black-and-white NTSC video (http://instruct1.cit.cornell.edu/courses/ee476/video/index.html). There are other projects out there doing this kind of thing as well. Somebody's using an SX chip (a 70MHz PIC clone) to generate color NTSC. I seem to recall that the usual interface hardware (for the monochrome) is two digital output pins with a two-resistor voltage divider. If you wanted grayscale, you'd need a DAC pin, or a resistor ladder. Generating the video this way uses most of these chips' time; they can only really do anything else during the VBI, or if they stop generating any interesting video for a while. So, yeah, a separate CPU for the display is probably a good idea. > 3/ Does the wireless communication link serve for mass storage, too? > What's the modern equivalent of the cassette player? Dunno --- maybe the VCR? Maybe the cassette player? Maybe an SD card? Maybe a SIM card? I think you can talk to an SD card with two or three pins, although at a lower speed than usual. I was thinking of using a DataFlash chip (a little under $2 for 4 or 8 megabits IIRC) onboard for mass storage. > One possibility might be something along these lines: > > http://www.internetwebkey.com/ (Summary: under-$5 tangible URL; plug it into the USB port and your browser visits an URL. I wonder if it's a HID keyboard device, or what?) > It seems to be reprogrammable, and while 56k may not be much for email, > it'd at least be a fair expansion for a machine that would otherwise > have only 1k of working store and 16K of eeprom. NAND flash seems to start at a price point around US$10 or US$20, at least from Digi-Key, and Atmel's DataFlash NOR seems to cost a minimum of US$1-$2, for which you can get half a megabyte IIRC. How hard would it be to redesign it to have dit and dah buttons that added characters that got typed when you plug it in? > [0] A former client of mine made IDE-drives, which at the time meant > that the embedded controller/RTOS that drove their drives was often > more sophisticated than the x86/DOS combination running applications on > the motherboard. At some point, the HP calculators carried by the > shuttle crew became more powerful than the shuttle's "main computer". I bet they crashed more often, though. > How common is technology inversion? There's no such thing as technology. > [1] A built-in display would be the most expensive component of this > interpretation of Kragen's device. What the heck are the $100 laptop > people using for a display? I see some nice QVGA displays available -- > but at much more like 150 USD and up. The $100 laptop people (OLPC) are inventing their own display because they aren't satisfied with the existing ones; presumably part of what they're dissatisfied with is the price. I'm offline at the moment, but here's what I find in my bytesforall archives on this laptop: http://www.pcadvisor.co.uk/news/index.cfm?newsid=3D6543 $100 laptop prototype shown off ... NECC members got an early look at one of the project's most innovative developments: a dual-mode display that can be easily viewed in natural and artificial light, which helps to reduce the machine's power consumption. Despite these efforts, the price tag of each computer still comes in at $130 to $140, although Negroponte and others involved in the project believe the cost will drop as component prices decrease. --- 'Our $100 laptops will run on human power' http://inhome.rediff.com/money/2006/apr/07laptop.htm April 07, 2006 ... In the case of the display, we have reduced the price to about $40. It is a dual-mode display, that is both rear-lit, colour (640x480) and front-lit B&W at 3X that resolution. ... 3M is helping with the display materials and backlight. Stephen Williams writes: > It would seem that a scanning laser display might be the most economical > ... Getting the price down might be hard, but it is fundamentally doable. Brian Atkins writes: > Microvision: http://microvision.blogspot.com/2006/08/mvis-msft.html I think I've speculated about building cheap retinal laser displays in the past on kragen-tol, and there are likely to be interesting new cheap display devices on the market soon: the prototypes I've seen of the waveguide heads-up display are amazing, the Siemens electrochromic display promises to be incredibly cheap next year (presumably subject to customer demand), E-Ink could in theory be very cheap too, and as described above, the OLPC people are inventing their own new display technology. But I don't want to commit error 33 (basing your research project on somebody else's research project).
