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I am reading Programming Embedded Systems
In this book, I came across this claim:
The amount of memory required can also affect the processor selection. In general, the register width of a processor establishes the upper limit of the amount of memory it can access (e.g., a 16-bit address register can address only 64 KB (216 ) memory locations). [*] <br />
<br />
[*] The narrower the register width, the more likely it is that the processor employs tricks such as multiple address spaces to support more memory. There are still embedded systems that do the job with a few hundred bytes. However, several thousand bytes is a more likely minimum, even on an 8-bit processor.<br />
THis really didn't make any sense to me. Can anyone shed some light on this?
"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson "Why is it drug addicts and computer afficionados are both called users?" - Clifford Stoll
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What part do you need clarified?
In a typical general purpose CPU, the number of bits in a register determines how much memory a CPU can address, since a memory address must be able to fit in the register. An 8-bit register can hold values from 0x00 to 0xFF and can only directly address 256 memory addresses. A 16-bit register can hold values from 0x0000 to 0xFFFF and can access memory addresses in that range, which is 64 KB.
In some CPUs they use tricks to get around that limitation, such as memory paging, where you somehow use more than one register to access banks of memory. For example, they might use one register to select the particular bank of memory, then another register to select the memory address within that bank.
In other cases they get away from von Neumann architecture and use Harvard architecture, where program and data memory are in separate banks, so you can effectively access a full bank for your program code and another full bank for the data.
CQ de W5ALT
Walt Fair, Jr., P. E.
Comport Computing
Specializing in Technical Engineering Software
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Consider it a history lesson from last century!
Software rusts. Simon Stephenson, ca 1994.
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I am trying to get started with embedded programming. I came across this website http://www.sparkfun.com/[^], which has a lot of tutorials and hardware.
However, I find the hardware a bit expensive. Like buying a circuit board for $30, plus a few other accessories would make it about a $100. Are their any websites that can sell hardware for a much cheaper price?
Also, My concern is that, for instance, I can buy a cordless phone for about $30 at best buy, but if I was to assemble that on my own, it would be over $200. So the second question is: how do companies assemble these devices and sell them for such a cheap price? Doesn't that mean the hardware they are getting/making is also very cheap? So where do they get it?
*I'm obviously a student, and have a really tight budget, please guide. =(
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Well, as far as price point of embedded kits... it depends on what you want, but $100 is a relatively inexpensive kit. Don't know if you're going to find much cheaper than that.
And as for the question about why you can buy something so cheap that would cost you a lot more to make yourself, well that's mass production at its best. Once a design has been and a prototype has been accepted, assembly lines (usually in a country where price of labor is also cheap) will be outfitted to mass produce circuit boards and the rest of the assemblies. Parts in bulk are usually significantly much cheaper to buy, so these mass producers buy things like resistors, capacitors, and so on in the thousands or millions (to see price differences in these small parts, go to digikey.com[^] and try random parts, and that's through a 3rd party vendor, big corporations have direct relationships with part manufacturers). The combined outcome of buying in bulk and assembly lines is significant savings to the consumer.
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I wasn't aware of how mass production can substantially reduce prices! Thanks for looking into my question and helping me out.
I'll definitely look into digikey.com.
Thanks!
"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson "Why is it drug addicts and computer afficionados are both called users?" - Clifford Stoll
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Compare the cost of even a surface mount resistor when you're buying 1 versus buying 15000. One is probably about 10-15 cents, 15000 is probably about a cent or less, I imagine if you buy a million units its probably a fraction of a cent each.
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Pathachiever wrote: So the second question is: how do companies assemble these devices and sell them for such a cheap price?
Give away the phone for free, ask money for the traffic 
Pathachiever wrote: Doesn't that mean the hardware they are getting/making is also very cheap? So where do they get it?
They might have decided to sell the product at a loss for six months to get a stable userbase and increase marketshare.
Isn't there a local radio shack in your neighbourhood? There's also some online stores like Conrad[^], depending on your location.
Bastard Programmer from Hell 
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You're right. I got my HTC Inspire for $45 at Sams Club, but probably took over $500 to make it.
"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson "Why is it drug addicts and computer afficionados are both called users?" - Clifford Stoll
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You're right, this has been the model that many have taken the last ~5-7 years, but usually only on most products that have a service associated with it.
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Eddy has it right. They are LOSING money on the phone, but they make it back on the contract you are tied into.
Same with printers and cartridges. How can a printer cost $50 and a cartridge $10?
Anyway, $100 for an electronics kit and tutorials is cheap IMO, espcially if it leads on to you learning something you can sell.
"The whole idea that carbon dioxide is the main cause of the recent global warming is based on a guess that was proved false by empirical evidence during the 1990s." climate-models-go-cold
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You have a point, but the device I am planning to make would require a Bluetooth adapter, video adapter, etc. That would probably go over $200. Still, I hope to learn something from it.
Thanks!
"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson "Why is it drug addicts and computer afficionados are both called users?" - Clifford Stoll
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Even at 200 bucks your education is worth it.
When you are earning that kind of money per day doing embedded code for PC comms devices, you will laugh that you ever thought it expemnsive.
"The whole idea that carbon dioxide is the main cause of the recent global warming is based on a guess that was proved false by empirical evidence during the 1990s." climate-models-go-cold
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If you want to start with something very basic, Ti has a board for only $4.30[^]. Dunno how far you can get beyond blinking LEDs without having to buy extra parts though....
Edit: ...and even then, the highest end cpu in the series only has 16k flash for your software and 512bytes of ram.
3x12=36
2x12=24
1x12=12
0x12=18
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Hey guy,
United ahead electronics.,ltd here, selling IC PARTS with good quality and low price.
contact me by eamil:diana@united-ahead-electronics.com
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Hi,
I have an mp3 player which I use for the radio in my car (much easier and faster than burning new CDs all the time).
Today, the radio suddenly wouldn't read from the mp3 player at all (it has been an issue all the time, but most of the time it has managed to start playing from it). So I took it inside and plugged it into my laptop, which then started installing the neccessary drivers, which I thought was odd, as it had been plugged in before. Then, when I tried accessing the drive, it said:
F:\ is not accessible. Incorrect funtion.
No matter what I did, I couldn't get access to it. So, I tried plugging it into my other pc (which is running XP), and it said:
The disk in drive F is not formatted. Do you want to format it now?
When clicking Yes, another box appears saying:
There is no disk in drive F. Insert a disk, and then try again.
Is there any hope of rescuing it? If yes, how?
Thanks in advance.
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If its an mp3 player, you probably don't want to format it anyway, since you'll probably end up wiping configuration files if not even software that it needs. Time for a new one... 
I've had one do this in the past, just ended up buying another after trying a few things.
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Dang. Oh well, it was only 120 DKK (~ $23) anyway 
Thanks.
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Considering how they mass produce these things, I'm surprised they even last as long as they do. 
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This one didn't even last a month before this problem arised. I guess you get what you pay for.
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oh... guess that is what you paid for...
...better luck on your next one!
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Hi!
I am trying to figure out how the video card talks to a projector. I am trying to code a small device that will be able to display images on the projector. I plan to expand this project, but before I even begin I need to know how I can talk to the projector.
I tried Google, Bing, and CodeProject but couldn't find the answer. I don't necessarily need the code, just a guide, or a paper explaining what happens behind the scenes and what data is exactly sent by the video card.
Thanks!
"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson "Why is it drug addicts and computer afficionados are both called users?" - Clifford Stoll
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A video card sends exactly the same signals to a projector as it does to a monitor. It could be VGA/SVGA/XGA/**GA or HDMI or component RGB or just about any other video standard (even composite video  ). A projector, after all, is just a monitor built funny.
Cheers,
Peter
Software rusts. Simon Stephenson, ca 1994.
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OK, here we go:
Preliminar information:
- No UPS sistem mounted.
- Several power cuts.
- Computer that was ON. (yes I know, I know...)
When I try to start up the computer:
The computer can't go further the bios message telling me that I should press F1 to continue as the BIOS has detected some changes (not specified).
If I press F1 nothing happens.
What would you do to recover that computer?
Thank you in advance!
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Richard, this looks as an interesting answer. I'll check it when I'll be in front of the computer again.
Thank you for answering!
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