NASA, and other engineering projects, use something called a design lifetime. For example, a spacecraft is designed to have a 0.95 probability of running for 5 years. This is the target that is used as the basis for many engineering decisions. How reliable do the components have to be, how much attitude control thruster fuel, how much excess solar cell capacity (solar cells degrade with age).
The spacecraft will probably last longer than 5 years. You don't want to spend more money, or add the weight of redundant systems or extra fuel and solar cells, if it is not needed to meet the mission requirements.
The disk drive in your computer was probably designed to last a certain length of time, say 5 years. When you see MTBF numbers on spec sheets, they are usually only valid for the design lifetime.
Landlines can be used fairly easily to provide something like T1 level speeds to the average user, where the digital network can stream both video, voice, data, etc. In the future, we can expect several times more bandwidth than that...
I think you are being very optimistic about the quality of the copper loops that are out there in the real world. There are loading coils, bridge taps, excessively long loops, crosstalk problems, corroded connections, missing or incorrect documentation, pair gain devices, loops that terminate at SLCs (subscriber loop carrier). Even if you had the money, you couldn't give everyone a T1 on the existing copper wiring. A T1, provisioned with HDSL boxes, requires two clean pairs that are less than 12,000 feet long.
As far as I can tell, most of the telephone companies are not investing any money in new copper subscriber loops that connect to a central office. They seem to be following the examples of the steel and railroad companies, using the cash generated by their decaying infrastructure to invest in more profitable businesses. Residential telephone service has never been a high margin business.
I learned a lot about programming by porting other people's programs to currently unsupported machines and operating systems. If you are really ambitious, get yourself something unusual like an Alpha. It's a great way to learn how to write portable code (No, the world is not a VAX) and you can learn many things that aren't in textbooks by reading other people's source code.
Is it really that hard to patch your system regulary as an Sysadmin?
As a part-time NT administrator, yes, it is hard to keep up with the patches on NT.
Service packs are easy to apply, they are not the problem. Someone hands you an unpatched NT box, what do you do? Assuming that you subscribe to the Microsoft Product Security Notification Service, you have to read a huge number of security bulletins. By my count, 60 bulletins from 1999 and 93 bulletins from 2000. For each one of these bulletins, you have to figure out if they are applicable to your system, and if so, download and apply a patch. This is a lot of work and can be confusing. For many NT system administrators, system administration is not their primary job, they are programmers or engineers. The security mailing lists are an even bigger time sink. They are high volume lists with a low signal-to-noise ratio.
...it helps us Chicanos cope with the fact that our land was stolen from us...
Oooh, look at the violence inherent in the system.
The Americans stole the land from the Spanish, who stole it from various Native Americans, who stole it from other Native Americans, and on and on it goes. You are going to have a hard time finding a decent piece of land on this planet that hasn't been "stolen" several times.
Instead of designing and building a complex digital telemetry system, why not use some old analog technology? Many early telemetry systems were analog. The sensors were connected to VCOs (voltage controlled oscillators), and the VCOs were mixed together and used to modulate a FM transmitter. This was a simple, cheap and reliable package. The data acquisition station had a FM receiver, its audio was fed to a bank of FM discriminators, one discriminator for each VCO. The outputs of the disciminators were connected to a stripchart and/or a set of ADCs for computer processing.
This works great for systems with a small number of parameters that need to be collected. The output of the FM receiver can be recorded on an ordinary analog magnetic tape recorder for archival storage and analysis. For some sample frequency plans, this page has tables listing the standard frequencies used in IRIG (Inter-Range Instrumentation Group) FDM (frequency division multiplex) systems.
I also came to realize that if my Tivo is made obselete, or if the service is dissolved, it will always function as a glorified VCR. I hope at the very least that ReplayTV ppl can say the same.
The last software update from ReplayTV added a manual record option, although I haven't tried using it yet.
What I want is a feature that will compensate for schedule shifts caused by football games or other sporting events. That might be tough to do.
"In the film world, 24-frame is the de facto standard, and it is much loved and considered integral to the `film' look," said Larry Thorpe, a Sony vice president responsible for the camera's development.
Much loved?
I think Larry Thorpe has been smoking too much crack. One of the really annoying things about film is the low frame rate. It requires cinematographers to avoid certain types of shots, since they will look terrible at 24 FPS. Higher frame rates, such as the 60 FPS format promoted by Douglas Trumbull, look much better.
The limit on the number of interrupts was solved by PCI. The PCI bus has four shared interrupt lines. We just need to get rid of all of the legacy ISA crap and build systems with USB, IEEE-1394 and PCI.
Pentium Pro processor. Possibly the most revolutionary CPU ever built
While it was a nice design, it was hardly the "most revolutionary CPU ever built". If you want something revolutionary, look at the IBM Stretch (7030), delivered in 1961. Most of the techniques used in today's microprocessors were pioneered in the 1960s. They are just a lot cheaper today.
Back in those days, many engineers would not design a part into a system unless it was available from more than one manufacturer (second sourced). That is why Intel licensed many second sources for the early 80x86 microprocessors. Later on, Intel decided that they could sell the chips even if they were the sole source.
The 80186 is basically an 8086 with a bunch of chipset and I/O features integrated on a single chip. It was popular for controller applications, like smart disk and serial I/O adapters. Tandy used it in a PC, but it had software compatibility problems with PC software due to the fact that the original IBM PC BIOS used interrupt vectors that Intel had reserved for their own use.
I used to work at a satellite tracking station in the South Atlantic ocean. We sometimes saw strange propagation disturbances with satellites that used VHF frequencies. The usual explanation was that the South Atlantic Anomaly was doing weird things to the ionosphere. Nobody seemed to know why it existed.
The other option is keeping everything hush-hush, and trying to be the only one that does something by the others not finding out how.
The latter hasn't been tried for decades
Trade secrets are still used today.
A patent lawyer once told me that some companies prefer trade secrets to patents. Trade secrets don't expire after N years.
X-rays are not going to damage a hard drive. The problem is the electric motors that are used for the conveyor belt. These generate strong magnetic fields that can erase or corrupt magnetic media. I've heard of similar problems with subway cars, big electric motors under the car that have been known to erase tapes in boxes that were set on the floor.
Exchange servers can talk IMAP & there's also a web-based interface that works nicely in Netscape on Linux.
I have a mail account that uses the web-based version of Exchange. The user interface and functionality is horrible. It looks like it was implemented as a check-list feature. Plus, I have to use a kludge that somebody cooked up to set/change two passwords, one for access to the NT domain and another for Exchange. The passwords expire on a regular basis and you need both passwords to access your email.
Yes, if you use baluns at each PC to compensate for the 72 Ohm characteristic impedance of CATV coax. Some companies used to sell them, I'm not sure if they are still being made.
I think many fail to realize that war -- whether conducted with knives or napalm, whether hand-to-hand or computerized -- is about killing.
From what I've read about modern military history, the goal of war is not to kill people, it is to destroy the combat effectiveness of the enemy's forces. This usually involves killing people, but that is not the objective.
Reliable DTMF detection is harder than you think. There is a TelCo test tape available for this purpose. From what I've heard, most DTMF decoders have difficulty with the test tape.
Groups of people should NEVER have the same rights (speech, political contributions, etc.) as individuals. The corporation as a legal entity should be banned.
This would be a very bad idea. Why shouldn't groups of like-minded people be able to organize and pool their resources for political purposes?
Did you ever notice that when someone agrees with a group, it is grass roots democracy. When they disagree with the group, it is an evil special interest group.
Slashdot Mirror
The disk drive in your computer was probably designed to last a certain length of time, say 5 years. When you see MTBF numbers on spec sheets, they are usually only valid for the design lifetime.
I think you are being very optimistic about the quality of the copper loops that are out there in the real world. There are loading coils, bridge taps, excessively long loops, crosstalk problems, corroded connections, missing or incorrect documentation, pair gain devices, loops that terminate at SLCs (subscriber loop carrier). Even if you had the money, you couldn't give everyone a T1 on the existing copper wiring. A T1, provisioned with HDSL boxes, requires two clean pairs that are less than 12,000 feet long.
As far as I can tell, most of the telephone companies are not investing any money in new copper subscriber loops that connect to a central office. They seem to be following the examples of the steel and railroad companies, using the cash generated by their decaying infrastructure to invest in more profitable businesses. Residential telephone service has never been a high margin business.
I learned a lot about programming by porting other people's programs to currently unsupported machines and operating systems. If you are really ambitious, get yourself something unusual like an Alpha. It's a great way to learn how to write portable code (No, the world is not a VAX) and you can learn many things that aren't in textbooks by reading other people's source code.
The * and # buttons were not on the original touch tone(TM) phones.
No, you don't.
There are areas that have 7-digit toll calls. Correlation is not causation.
As a part-time NT administrator, yes, it is hard to keep up with the patches on NT.
Service packs are easy to apply, they are not the problem. Someone hands you an unpatched NT box, what do you do? Assuming that you subscribe to the Microsoft Product Security Notification Service, you have to read a huge number of security bulletins. By my count, 60 bulletins from 1999 and 93 bulletins from 2000. For each one of these bulletins, you have to figure out if they are applicable to your system, and if so, download and apply a patch. This is a lot of work and can be confusing. For many NT system administrators, system administration is not their primary job, they are programmers or engineers. The security mailing lists are an even bigger time sink. They are high volume lists with a low signal-to-noise ratio.
Oooh, look at the violence inherent in the system.
The Americans stole the land from the Spanish, who stole it from various Native Americans, who stole it from other Native Americans, and on and on it goes. You are going to have a hard time finding a decent piece of land on this planet that hasn't been "stolen" several times.
clickety, clack, clickety...
N3499 -- Orbital Maneuver Initiated
Instead of designing and building a complex digital telemetry system, why not use some old analog technology? Many early telemetry systems were analog. The sensors were connected to VCOs (voltage controlled oscillators), and the VCOs were mixed together and used to modulate a FM transmitter. This was a simple, cheap and reliable package. The data acquisition station had a FM receiver, its audio was fed to a bank of FM discriminators, one discriminator for each VCO. The outputs of the disciminators were connected to a stripchart and/or a set of ADCs for computer processing. This works great for systems with a small number of parameters that need to be collected. The output of the FM receiver can be recorded on an ordinary analog magnetic tape recorder for archival storage and analysis. For some sample frequency plans, this page has tables listing the standard frequencies used in IRIG (Inter-Range Instrumentation Group) FDM (frequency division multiplex) systems.
The last software update from ReplayTV added a manual record option, although I haven't tried using it yet.
What I want is a feature that will compensate for schedule shifts caused by football games or other sporting events. That might be tough to do.
No, Iridium was designed for low bit rate (2400 BPS), low fidelity, voice communications.
Much loved?
I think Larry Thorpe has been smoking too much crack. One of the really annoying things about film is the low frame rate. It requires cinematographers to avoid certain types of shots, since they will look terrible at 24 FPS. Higher frame rates, such as the 60 FPS format promoted by Douglas Trumbull, look much better.
Clone some Hawaiian shamans?
It's a little weird, but it might work.
The limit on the number of interrupts was solved by PCI. The PCI bus has four shared interrupt lines. We just need to get rid of all of the legacy ISA crap and build systems with USB, IEEE-1394 and PCI.
While it was a nice design, it was hardly the "most revolutionary CPU ever built". If you want something revolutionary, look at the IBM Stretch (7030), delivered in 1961. Most of the techniques used in today's microprocessors were pioneered in the 1960s. They are just a lot cheaper today.
Back in those days, many engineers would not design a part into a system unless it was available from more than one manufacturer (second sourced). That is why Intel licensed many second sources for the early 80x86 microprocessors. Later on, Intel decided that they could sell the chips even if they were the sole source.
The 80186 is basically an 8086 with a bunch of chipset and I/O features integrated on a single chip. It was popular for controller applications, like smart disk and serial I/O adapters. Tandy used it in a PC, but it had software compatibility problems with PC software due to the fact that the original IBM PC BIOS used interrupt vectors that Intel had reserved for their own use.
I used to work at a satellite tracking station in the South Atlantic ocean. We sometimes saw strange propagation disturbances with satellites that used VHF frequencies. The usual explanation was that the South Atlantic Anomaly was doing weird things to the ionosphere. Nobody seemed to know why it existed.
Trade secrets are still used today.
A patent lawyer once told me that some companies prefer trade secrets to patents. Trade secrets don't expire after N years.
X-rays are not going to damage a hard drive. The problem is the electric motors that are used for the conveyor belt. These generate strong magnetic fields that can erase or corrupt magnetic media. I've heard of similar problems with subway cars, big electric motors under the car that have been known to erase tapes in boxes that were set on the floor.
I have a mail account that uses the web-based version of Exchange. The user interface and functionality is horrible. It looks like it was implemented as a check-list feature. Plus, I have to use a kludge that somebody cooked up to set/change two passwords, one for access to the NT domain and another for Exchange. The passwords expire on a regular basis and you need both passwords to access your email.
Yes, if you use baluns at each PC to compensate for the 72 Ohm characteristic impedance of CATV coax. Some companies used to sell them, I'm not sure if they are still being made.
From what I've read about modern military history, the goal of war is not to kill people, it is to destroy the combat effectiveness of the enemy's forces. This usually involves killing people, but that is not the objective.
Reliable DTMF detection is harder than you think. There is a TelCo test tape available for this purpose. From what I've heard, most DTMF decoders have difficulty with the test tape.
This would be a very bad idea. Why shouldn't groups of like-minded people be able to organize and pool their resources for political purposes?
Did you ever notice that when someone agrees with a group, it is grass roots democracy. When they disagree with the group, it is an evil special interest group.