Ummm, no. That isn't how those spinner guys work. You are talking about a Crooke's Radiometer, and it isn't light pressure that causes the vanes to spin. If it was light pressure causing it to spin, the white side should be getting "pushed". What causes the vanes to spin is the small amount of gas still in the bulb bouncing more energetically off the warmer black vane, which is why the black side of the vanes gets pushed.
The bend in the flag due to light pressure would be measurable, but only by very sensitive equipment. The momentum of a photon is very small, even with the intensity of the sun, it still doesn't amount to much. Compared to the gravitational force of the moon, it might as well not be considered at all.
Dunno why you guys got modded to 3, you're talking rubbish. The flag doesn't flutter. The "sun wind" isnt even enough pressure to make michael jacksons penis flutter either.
Dunno why you posted without actually reading what I wrote:
The light from the sun does have a measurable force, but it is very very small relative to everything else affecting things on the moon
The flag flutters because of the "sun wind", i.e. light pressure. If americans would have better physic lessons, they would learn about it..
Wow, I hadn't heard anyone use that one before... Um, how much force does the light from the sun exert on a flag that small? Is the force relatively constant? Why isn't the dust on the moon blowing under this "sun wind"?
The light from the sun does have a measurable force, but it is very very small relative to everything else affecting things on the moon (isn't even strong enough to blow the moon dust around). The flag was waving in the breeze because the the vibration caused by sticking it in the ground had very little damping in the flag fabric without the presence of air. Only the miniscule friction cause within the material itself damped the flags movement so it "fluttered" at its resonant frequency.
I thought this was pretty ridiculous when I first read it, so I did some research and read up on the part 15 and part 97 regs... but you're right, if you have a radio license, part 15 regs don't apply to you, and part 97's do. And you could, theoretically at least, crank the power at the transmitter up to 100W. One thing stopping you is part 97 section 313(a): An amateur station must use the minimum transmitter power necessary to carry out the desired communications. 100W is only perfectly legal if that is how much you need. I'm pretty sure if you work the numbers you could show that no two line of sight points within 50km of the surface of the earth would require that much power.
So even with a license, they would probably have to keep the power down to 250mW unless they could show they needed more than 300kbps. The FCC is far less lenient with licensed radio operators than amateurs and cranking the power up well above the minimum necessary could result in your licensed being revoked.
Also to fall under part 97, while transmitting you must have a control operator manning the equipment, or if you have an automatically controlled station your bandwidth limitation is 500Hz (I'm not sure that is even possible with 2.4GHz).
However, if you build one and it does not meet FCC regs (transmits outside of your channel, too much power, bad signal, etc) then you're in trouble.
'Trouble' being a relative thing, the FCC regs acknowledge that hobbyists may not have the necessary equipment to test their home-built transmitter's total power output. They are expected to employ best engineering practices to ensure that their device probably doesn't violate the regs. The first step of "trouble" you'd get in for a home built transmitter that tramples everybody's signal is someone showing up at your door telling you to turn your transmitter off.
I have SBC's "Enhanced DSL", which is now called something else. It's 5 static IP addresses on an ADSL line. Every complaint I have ever heard from someone around here about SBC's DSL service has been related to PPPoE. Since my IP addresses are static, I haven't had those problems. The quality of the service has been very high. In two years, I think I've noticed a total of maybe 8 hours cumulative when I wanted to use the internet and couldn't, about 3 hours of that time was at 2 o'clock in the morning when they were probably resetting the DSLAM or something.
They also let me run servers on my static IP, I don't know if they've changed that rule or not. Not that you could run much of a server on 128K, it's still enough for email and a web site for friends and family.
Are you sure about this? A search for "SDSL" on SBC's web site turned up nothing but glossary hits. The $65/mo service they do have is 5 static IPs on an ADSL 1.5/128 connection.
Can you give me a nice GUI to administer my webserver? Great! But I want (1) textual manipulation [e.g., of config files], (2) command-line manipulation (via CLI utilities), and (3) programmatic manipulation (via libraries) as well. And I also want documentation for all of the above.
Make your config file well formed XML and you can have all four.
What an odd and disturbing trend. People publicly admitting that they are unable to perform tasks that tens of thousands of other people have performed with little or no trouble.
Okay, I call bullshit. Tens of thousands of other people have performed the task, but they did not do it with "little or no trouble" unless they already had significant knowledge of Debian. Nobody has little or no trouble the first time the install Debian. I've been using Linux since 0.99pl14 and I've written a miniscule portion of the code in the kernel, and I _hate_ installing Debian, but do so because after I install it I feel that I have installed a system which contains only the things I want (i.e. thinnest possible system).
Any corporate entity I talk to I steer way clear of Debian because their tech people would use it to deride linux as completely unusable. RedHat and Mandrake are much easier. In the time it took me to get 1 good Debian install, I could have installed Mandrake 4 times.
I think you didn't read the article, and you are confused about the terms you are using. OSS work typically has very low usability but very high utility. You seem to equate usability with utility. The article defines usability very clearly and frankly, OSS falls flat on its face. You also don't understand good software design if you think GUI bells and whistles are added for marketing.
The number of "tiers" refers to the number of players (apps) between a client application and the data or service it wants. A two tier system is almost always called "client-server", because those are the only two players involved. In the trade if the client is a custom app and the server is a database, this arrangement is usually referred to as "thick client".
A site like slashdot is probably 3 tier because data travels client-server-db. The obvious reason to do 3 tier is the web. Web browsers shouldn't have to support running code to do complex SQL queries to some database. However there are a host of other reasons to separate database access from the client like security or connection pooling. You don't really want your db to suffer 100,000 simultaneous accesses, much better to put in a middle tier that maintains a queue of those wanting access and a pool of open connections to execute the queries. This set up where the middle tier does the db access on the client's behalf is usually called "thin client".
Besides the whole web browser model, other 3-tier (or n-tier as we like to call them, although n is rarely greater than 4) technologies in common use (or at least that I've used) are CORBA (cross platform and language standard) and EJB (Java standard).
Furthermore, this guy somehow thinks that removing the #define is an effective barrier to piracy? I think I heard of something called a symbol table at some point.... maybe that would help black-beard?
Symbol tables usually only include references to things you are setting memory aside for (variables and functions) - #define's would generally not show up. It's debugging information that is usually not included in a production build anyway. It would still be relatively easy to recover whatever the #define was anyway, regardless of the build.
Can you back that up with any kind of evidence? Even anecdotal?
A person who believes that removing constants from your source code imparts protection from international copyright hijacking, probably can't back up anything. I'm going to take a wild guess and say this guy hasn't written any real assembly source code in his life, or he'd know just how stupid his assertion is. If you're cutting out constants (not macros), I'm betting that in 30 minutes I could be set up to recover one of them, and each one after that would take about 30 seconds. Why can't we moderate articles as -1 Troll??
CD-R ~ 5 years before you will start getting some unreadable CDs out of a fair sized batch Tape ~ 20 years before the tape itself degrades to the point where you'll notice
I'm assuming that a tape that lasts 20 years before noticeable loss is much better than a low cost bulk tape. You should compare it to a similar CD-R.
A high archival quality CD-R costs about $1.50/unit and has a shelf life of over two hundred (200) years. This is significantly longer than a production pressed CD is expected to live. Archival CD-Rs are the way to go.
if stock market lost 3 trillions - that means at least that much money changed hands.
No, it doesn't mean that at all. You never studied economics, did you? You could not convert the value of the stock market into liquidity. There simply isn't that much money.
Yes, but right now 2GHz is too much. That's why AMD is taking its focus off making ever faster processors... too few people want them.
When is 5GHz not going to be nearly enough? Judging by soft high end chip sales, it isn't going to be in the next three years. That's why AMD is doing this.
One often has to make changes to header files fairly high up in the dependency chain..:/
It is very typical for me to have to spend more than 70% of my time in a day just WAITING for the computer to do one thing or another.
It sounds like you have an architecture problem. A serious one too if you have to make changes to pieces for which substantially all of the software is dependent on a regular basis.
Man, 3D gaming, video & image editing _needs_ processing power. Besides you'll be more comfortable with faster processors in developing, believe me. (Compile time counts.)
I play counterstrike regularly. OpenGL with wait for vsync off. I sit at 100fps nearly the entire game. Complex scenes in UT2K3 still see excellent frame rates, and much of that is work done by the GeForce 3. So why is it I need more than 1GHz for 3D gaming?
99% of my time spent developing is writing code, thinking about code, and designing the architecture of the system or subsystem I'm working on. When would I need a 2GHz processor to increase compile time? Especially since the compile time is mostly I/O bound on disk access.
My video & image editing has never needed anything faster than my 1GHz machine with one exception - compressing an hour of raw footage into mpeg. The tools let me preview the entire thing from the raw footage though, so I don't have to wonder what the final copy will look like. That simply runs overnight and I never notice that it could have finished at 12am instead of 6am. I don't care.
AMD... said that making semiconductors smaller, cheaper and faster was no longer the key for an effective strategy.
They said it's no longer the key, which doesn't mean they won't invest some resources into smaller/cheaper/faster. I think they are just reacting to a market that is saying "for the most part your last generation of processors were small, cheap and fast enough - I don't need an upgrade right now, thanks".
The reality is that many people with 300MHz machines don't feel compelled to upgrade at all. Least of all to an Athlon XP 2800+. When these people do decide to upgrade to a 1GHz machine, AMD will be in there competing with Intel. It's the high end freaks who will feel AMDs absence. They just aren't a big enough market to justify the expense of developing and producing better high end processors.
Yes, I can't really understand why AMD would pull out of potentially the most lucrative area of the chip market, having gained an extremely tough-to-gain foothold there!
They aren't pulling out of the PC processor market, they are saying that demand for high end processors is weak and the cost of R&D to produce 5GHz+ chips may not be made back. So they are changing their focus away from competing with Intel on the very top end. When the market picks back up and suddenly everybody is demanding enough processing power to run their own simulation of a thermonuclear detonation, then AMD will spend more R&D money on top end processors. They won't stop producing Athlons, they will stop investing huge chunks of money into making faster chips.
For most people like myself who only use their computer for 3D gaming, software development, video & image editing, writing papers, checking email, talking on IRC and reading/., well for us 1GHz is plenty.
Much of this is a response to the fact that they're asking for a $300million note, and the market they are in is depressed.
It is simple, tar -xvzf linux-{current}.tar.gz. cd linux; make menuconfig; make dep bzImage modules modules_install
You're joking, right? How many options in 2.5.47 must be selected in order for your run of the mill $9 generic PS/2 keyboard to work? I can't tell you how much fun it was building 2.5.47, missing one *somewhere* and suddenly I couldn't do anything because my keyboard stopped working.
The kernel only has an expert mode. It would be nice if there were a higher order config that asked you basic questions and built the things you were most likely to need, with the option of going into a more expert mode if you needed to fine tune something.
When we're all dead, people will remember us for the kind deeds we did while we were walking the streets and talking the talk. The little league team you coached
Yes!
volunteering at a Mormon church
Yes!
and all those bake sales for the PTA will be what you were best known for.
Yes!
You are talking about deeds done for noble causes, for the public good, and for positive karma (no, not THAT karma:) ). I don't think that putting out a fire for a for-profit corporate entity is in the same ballpark.
The only shitty part is you'll just be tossed into the Hudson River because you and your socialist family members don't have the money for a proper funeral and burial.
You could always donate your body for academic research. Hopefully that academic research won't be the effect of the Hudson River on cadavers. Mother Theresa lived to help the needy, her funeral wasn't too shabby.
Just make up an invoive for your labor, you can even charge an on-call fee. A court will back you up as well. Nobody can expect someone to work for free.
No, the court won't back him up. It's the same thing as your friend next door asking if you could take a look at what is wrong with his Windows 95 box. You can't retroactively charge a fee if you didn't agree on one up front. Whether you want to call it work done for good will, pro bono, volunteer or on spec, you can't charge unless both parties understand before hand there will be a charge or both parties agree afterwards there should be a charge.
Never work for a corporate entity free of consideration. If you're inexperienced, that consideration may just be "experience". If they laid you off, you may work on speculation that they will think of you first when they can start hiring again. But if you've been out of work for 5 months, I reccomend that consideration be cold hard cash.
Close to all the replies so far have been this, I agree... but one has to wonder... Why on earth did he agree to do this at all without an agreement up front for payment?
Everyone, your employer is not your neurotic pot buddy from college who calls you out of the blue every now and then for help. They are a legal entity that exchanges labor for cash. If your former employer needs help with something, you have the responsibility for asking what kind of consideration they are going to give you for your labor... and get it in writing up front.
No wonder people are getting laid off! Employers are learning they'll work for free "just to be kind".
Slashdot Mirror
Ummm, no. That isn't how those spinner guys work. You are talking about a Crooke's Radiometer, and it isn't light pressure that causes the vanes to spin. If it was light pressure causing it to spin, the white side should be getting "pushed". What causes the vanes to spin is the small amount of gas still in the bulb bouncing more energetically off the warmer black vane, which is why the black side of the vanes gets pushed.
The bend in the flag due to light pressure would be measurable, but only by very sensitive equipment. The momentum of a photon is very small, even with the intensity of the sun, it still doesn't amount to much. Compared to the gravitational force of the moon, it might as well not be considered at all.
Dunno why you guys got modded to 3, you're talking rubbish. The flag doesn't flutter.
The "sun wind" isnt even enough pressure to make michael jacksons penis flutter either.
Dunno why you posted without actually reading what I wrote:
The light from the sun does have a measurable force, but it is very very small relative to everything else affecting things on the moon
The flag flutters because of the "sun wind", i.e. light pressure. If americans would have better physic lessons, they would learn about it..
Wow, I hadn't heard anyone use that one before... Um, how much force does the light from the sun exert on a flag that small? Is the force relatively constant? Why isn't the dust on the moon blowing under this "sun wind"?
The light from the sun does have a measurable force, but it is very very small relative to everything else affecting things on the moon (isn't even strong enough to blow the moon dust around). The flag was waving in the breeze because the the vibration caused by sticking it in the ground had very little damping in the flag fabric without the presence of air. Only the miniscule friction cause within the material itself damped the flags movement so it "fluttered" at its resonant frequency.
I thought this was pretty ridiculous when I first read it, so I did some research and read up on the part 15 and part 97 regs... but you're right, if you have a radio license, part 15 regs don't apply to you, and part 97's do. And you could, theoretically at least, crank the power at the transmitter up to 100W. One thing stopping you is part 97 section 313(a): An amateur station must use the minimum transmitter power necessary to carry out the desired communications. 100W is only perfectly legal if that is how much you need. I'm pretty sure if you work the numbers you could show that no two line of sight points within 50km of the surface of the earth would require that much power.
So even with a license, they would probably have to keep the power down to 250mW unless they could show they needed more than 300kbps. The FCC is far less lenient with licensed radio operators than amateurs and cranking the power up well above the minimum necessary could result in your licensed being revoked.
Also to fall under part 97, while transmitting you must have a control operator manning the equipment, or if you have an automatically controlled station your bandwidth limitation is 500Hz (I'm not sure that is even possible with 2.4GHz).
However, if you build one and it does not meet FCC regs (transmits outside of your channel, too much power, bad signal, etc) then you're in trouble.
'Trouble' being a relative thing, the FCC regs acknowledge that hobbyists may not have the necessary equipment to test their home-built transmitter's total power output. They are expected to employ best engineering practices to ensure that their device probably doesn't violate the regs. The first step of "trouble" you'd get in for a home built transmitter that tramples everybody's signal is someone showing up at your door telling you to turn your transmitter off.
I have SBC's "Enhanced DSL", which is now called something else. It's 5 static IP addresses on an ADSL line. Every complaint I have ever heard from someone around here about SBC's DSL service has been related to PPPoE. Since my IP addresses are static, I haven't had those problems. The quality of the service has been very high. In two years, I think I've noticed a total of maybe 8 hours cumulative when I wanted to use the internet and couldn't, about 3 hours of that time was at 2 o'clock in the morning when they were probably resetting the DSLAM or something.
They also let me run servers on my static IP, I don't know if they've changed that rule or not. Not that you could run much of a server on 128K, it's still enough for email and a web site for friends and family.
Are you sure about this? A search for "SDSL" on SBC's web site turned up nothing but glossary hits. The $65/mo service they do have is 5 static IPs on an ADSL 1.5/128 connection.
Can you give me a nice GUI to administer my webserver? Great! But I want (1) textual manipulation [e.g., of config files], (2) command-line manipulation (via CLI utilities), and (3) programmatic manipulation (via libraries) as well. And I also want documentation for all of the above.
Make your config file well formed XML and you can have all four.
What an odd and disturbing trend. People publicly admitting that they are unable to perform tasks that tens of thousands of other people have performed with little or no trouble.
Okay, I call bullshit. Tens of thousands of other people have performed the task, but they did not do it with "little or no trouble" unless they already had significant knowledge of Debian. Nobody has little or no trouble the first time the install Debian. I've been using Linux since 0.99pl14 and I've written a miniscule portion of the code in the kernel, and I _hate_ installing Debian, but do so because after I install it I feel that I have installed a system which contains only the things I want (i.e. thinnest possible system).
Any corporate entity I talk to I steer way clear of Debian because their tech people would use it to deride linux as completely unusable. RedHat and Mandrake are much easier. In the time it took me to get 1 good Debian install, I could have installed Mandrake 4 times.
I think you didn't read the article, and you are confused about the terms you are using. OSS work typically has very low usability but very high utility. You seem to equate usability with utility. The article defines usability very clearly and frankly, OSS falls flat on its face. You also don't understand good software design if you think GUI bells and whistles are added for marketing.
The number of "tiers" refers to the number of players (apps) between a client application and the data or service it wants. A two tier system is almost always called "client-server", because those are the only two players involved. In the trade if the client is a custom app and the server is a database, this arrangement is usually referred to as "thick client".
A site like slashdot is probably 3 tier because data travels client-server-db. The obvious reason to do 3 tier is the web. Web browsers shouldn't have to support running code to do complex SQL queries to some database. However there are a host of other reasons to separate database access from the client like security or connection pooling. You don't really want your db to suffer 100,000 simultaneous accesses, much better to put in a middle tier that maintains a queue of those wanting access and a pool of open connections to execute the queries. This set up where the middle tier does the db access on the client's behalf is usually called "thin client".
Besides the whole web browser model, other 3-tier (or n-tier as we like to call them, although n is rarely greater than 4) technologies in common use (or at least that I've used) are CORBA (cross platform and language standard) and EJB (Java standard).
I think the fourth sentence in the article was:
In other words, part of the delivery package for any software purchase should be a copy of the source files.
I don't think he was limiting it to work done for hire. I think it was open to any software purchase.
Furthermore, this guy somehow thinks that removing the #define is an effective barrier to piracy? I think I heard of something called a symbol table at some point.... maybe that would help black-beard?
Symbol tables usually only include references to things you are setting memory aside for (variables and functions) - #define's would generally not show up. It's debugging information that is usually not included in a production build anyway. It would still be relatively easy to recover whatever the #define was anyway, regardless of the build.
Can you back that up with any kind of evidence? Even anecdotal?
A person who believes that removing constants from your source code imparts protection from international copyright hijacking, probably can't back up anything. I'm going to take a wild guess and say this guy hasn't written any real assembly source code in his life, or he'd know just how stupid his assertion is. If you're cutting out constants (not macros), I'm betting that in 30 minutes I could be set up to recover one of them, and each one after that would take about 30 seconds. Why can't we moderate articles as -1 Troll??
CD-R ~ 5 years before you will start getting some unreadable CDs out of a fair sized batch
Tape ~ 20 years before the tape itself degrades to the point where you'll notice
I'm assuming that a tape that lasts 20 years before noticeable loss is much better than a low cost bulk tape. You should compare it to a similar CD-R.
A high archival quality CD-R costs about $1.50/unit and has a shelf life of over two hundred (200) years. This is significantly longer than a production pressed CD is expected to live. Archival CD-Rs are the way to go.
if stock market lost 3 trillions - that means at least that much money changed hands.
No, it doesn't mean that at all. You never studied economics, did you? You could not convert the value of the stock market into liquidity. There simply isn't that much money.
5GHz isnt going to be nearly enough. ;>
Yes, but right now 2GHz is too much. That's why AMD is taking its focus off making ever faster processors... too few people want them.
When is 5GHz not going to be nearly enough? Judging by soft high end chip sales, it isn't going to be in the next three years. That's why AMD is doing this.
One often has to make changes to header files fairly high up in the dependency chain .. :/
It is very typical for me to have to spend more than 70% of my time in a day just WAITING for the computer to do one thing or another.
It sounds like you have an architecture problem. A serious one too if you have to make changes to pieces for which substantially all of the software is dependent on a regular basis.
Man, 3D gaming, video & image editing _needs_ processing power. Besides you'll be more comfortable with faster processors in developing, believe me. (Compile time counts.)
I play counterstrike regularly. OpenGL with wait for vsync off. I sit at 100fps nearly the entire game. Complex scenes in UT2K3 still see excellent frame rates, and much of that is work done by the GeForce 3. So why is it I need more than 1GHz for 3D gaming?
99% of my time spent developing is writing code, thinking about code, and designing the architecture of the system or subsystem I'm working on. When would I need a 2GHz processor to increase compile time? Especially since the compile time is mostly I/O bound on disk access.
My video & image editing has never needed anything faster than my 1GHz machine with one exception - compressing an hour of raw footage into mpeg. The tools let me preview the entire thing from the raw footage though, so I don't have to wonder what the final copy will look like. That simply runs overnight and I never notice that it could have finished at 12am instead of 6am. I don't care.
AMD ... said that making semiconductors smaller, cheaper and faster was no longer the key for an effective strategy.
They said it's no longer the key, which doesn't mean they won't invest some resources into smaller/cheaper/faster. I think they are just reacting to a market that is saying "for the most part your last generation of processors were small, cheap and fast enough - I don't need an upgrade right now, thanks".
The reality is that many people with 300MHz machines don't feel compelled to upgrade at all. Least of all to an Athlon XP 2800+. When these people do decide to upgrade to a 1GHz machine, AMD will be in there competing with Intel. It's the high end freaks who will feel AMDs absence. They just aren't a big enough market to justify the expense of developing and producing better high end processors.
Yes, I can't really understand why AMD would pull out of potentially the most lucrative area of the chip market, having gained an extremely tough-to-gain foothold there!
/., well for us 1GHz is plenty.
They aren't pulling out of the PC processor market, they are saying that demand for high end processors is weak and the cost of R&D to produce 5GHz+ chips may not be made back. So they are changing their focus away from competing with Intel on the very top end. When the market picks back up and suddenly everybody is demanding enough processing power to run their own simulation of a thermonuclear detonation, then AMD will spend more R&D money on top end processors. They won't stop producing Athlons, they will stop investing huge chunks of money into making faster chips.
For most people like myself who only use their computer for 3D gaming, software development, video & image editing, writing papers, checking email, talking on IRC and reading
Much of this is a response to the fact that they're asking for a $300million note, and the market they are in is depressed.
It is simple , tar -xvzf linux-{current}.tar.gz.
cd linux; make menuconfig ; make dep bzImage modules modules_install
You're joking, right? How many options in 2.5.47 must be selected in order for your run of the mill $9 generic PS/2 keyboard to work? I can't tell you how much fun it was building 2.5.47, missing one *somewhere* and suddenly I couldn't do anything because my keyboard stopped working.
The kernel only has an expert mode. It would be nice if there were a higher order config that asked you basic questions and built the things you were most likely to need, with the option of going into a more expert mode if you needed to fine tune something.
When we're all dead, people will remember us for the kind deeds we did while we were walking the streets and talking the talk. The little league team you coached
:) ). I don't think that putting out a fire for a for-profit corporate entity is in the same ballpark.
Yes!
volunteering at a Mormon church
Yes!
and all those bake sales for the PTA will be what you were best known for.
Yes!
You are talking about deeds done for noble causes, for the public good, and for positive karma (no, not THAT karma
The only shitty part is you'll just be tossed into the Hudson River because you and your socialist family members don't have the money for a proper funeral and burial.
You could always donate your body for academic research. Hopefully that academic research won't be the effect of the Hudson River on cadavers. Mother Theresa lived to help the needy, her funeral wasn't too shabby.
Just make up an invoive for your labor, you can even charge an on-call fee. A court will back you up as well. Nobody can expect someone to work for free.
No, the court won't back him up. It's the same thing as your friend next door asking if you could take a look at what is wrong with his Windows 95 box. You can't retroactively charge a fee if you didn't agree on one up front. Whether you want to call it work done for good will, pro bono, volunteer or on spec, you can't charge unless both parties understand before hand there will be a charge or both parties agree afterwards there should be a charge.
Never work for a corporate entity free of consideration. If you're inexperienced, that consideration may just be "experience". If they laid you off, you may work on speculation that they will think of you first when they can start hiring again. But if you've been out of work for 5 months, I reccomend that consideration be cold hard cash.
Close to all the replies so far have been this, I agree... but one has to wonder... Why on earth did he agree to do this at all without an agreement up front for payment?
Everyone, your employer is not your neurotic pot buddy from college who calls you out of the blue every now and then for help. They are a legal entity that exchanges labor for cash. If your former employer needs help with something, you have the responsibility for asking what kind of consideration they are going to give you for your labor... and get it in writing up front.
No wonder people are getting laid off! Employers are learning they'll work for free "just to be kind".