At 05:10 AM 3/4/98 +0000, Mel Tsai wrote: >>Keep in mind as well that the 4mhz is the max speed of the processor, >>that does not mean its ever going to get to 4mhz while doing some >>processing (in fact, it probably won't). A 6mhz z80 in a calculator (The >>TI-8x series) can be clocked at 2mhz. Say you can reach 2mhz with the z80 >>in the gameboy. Don't forget now that you'll want some I/O there, because >>of the need of a hard drive and other such devices. After this, what speed >>do you think you'll reach? > >Ummm :) > >No processor switches clock rates during operation (well actually some >do, but generally small embedded processors don't). I was referring to the general latency of the clock speed due to applications and physical addons slowing it down (whether it has to scan ports to run something, etc., etc.) >Problem though is that the complexity of these systems rises >exponentially with processor power. You have to guage what you want >with how much time you're willing to spend developing. While the NEC >VR chips are cheap, super high performance, and use very little power, >the simplest VR chip is a 120 pin quad flat package! Most of the VR's >suitible for wearables (the VR41xx series) are 180 or more pins. >There's *no way* you can homebuild a circuit board in which this chip >can be mounted. You must resort to expensive board fabrication >houses, and expect to pay $200+ just for a few prototype boards. >Couple this with the fact that most of these 32 bit chips require 16 >or even 32 bit wide memory datapaths, which makes your board >complexity go through the roof, unless you can find chips with large >on-chip memories. But even still you'll have to add RAM which rarely >ever comes on-chip. The PDA manufacturers can get away with using >these big complicated chips because they included huge and expensive >FPGA chipsets along with 4 or even 8 layer printed circuit boards, >which allows their entire system to fit in small spaces. Few people >can afford these luxuries when their goal is a low cost wearable. Unless of course some sort of deal came through =) It has been very... prevalent... in my thinking that the production of a low-cost (or would-be low-cost, with mass production) wearable computer would be an intriguing idea for NEC.. perhaps interesting enough to put it into production, bringing a nice and cheap wearable to the general market (possibly bringing the intent of wearable systems to the forefont at the cost of commercialist ideas for them). - Joseph Gaffney -- http://www.thethinker.com/members/gaffney/ - http://www.ArchAgency.com/
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