If you assemble 8 bytes (with parity) into a 64 bit word, you can use SECDED (single error correct, double error detect) ECC on the 64 bit word. 8 check bits are needed for ECC on a 64 bit word.
I suspect that the television networks will have something to say about it. They may require their affiliates to carry the prime time network feed in high definition (1080i or 720p). NBC is not going to like competing against another network's high definition signal with a standard definition signal.
For anyone interested in the history of HDTV, I recommend the book "Defining Vision: The Battle for the Future of Television" by Joel Brinkley (ISBN 0-15-100087-5). It is an interesting account of how money and politics, not technical merit, were responsible for the creation of HDTV.
Part of the rationale for switching from NTSC to ATSC (HDTV) is to recover some of the huge amounts of spectrum that are currently allocated to NTSC. NTSC makes very inefficient use of the VHF/UHF spectrum.
The original plan was to move all television stations to a smaller UHF band, freeing up the VHF channels and some of the UHF channels. It now looks like at least some of the VHF channels will remain allocated to television.
The FCC wants to auction off some of the recovered channels and reallocate some of the channels to other services, such as land mobile.
The television broadcasters would have lost even more spectrum without HDTV. A digital SDTV (standard definition) system would have greatly reduced their spectrum requirements.
The NAB (National Association of Broadcasters) was originally interested in HDTV as a means of protecting their spectrum allocations from other services (Motorola and land mobile). They needed to give the FCC a reason why it shouldn't reallocate large portions of the sparsely occupied UHF band to other services.
As a side effect of tracking down spammers and liquidating them, I found many low budget web sites that accepted credit card orders and stored them in globally readable files on the web server. If you read the source for these web pages, you can see how they process the data submitted by their customers. Many just take the data from the form and append it to a file on the web server.
One way to do this is to put a gatekeeper in between the order entry system and the secure database. The gatekeeper system is responsible for checking and forwarding all messages to/from the secure database. The gatekeeper has its own database of message types and message templates. Each incoming message is checked for a valid message type and the contents are compared to the message template for that message type. Only messages that pass all tests are forwarded. All others are logged and printed for analysis by the security office.
I read the article and I don't understand how the lack of free software is going to prevent anyone from creating and distributing video content. Sony will happily sell me a video camera, VTR and other expensive gadgets without any restrictions on content. The software vendors will also sell me encoding software and video server software without any restrictions on content. So what's the problem? The television networks had power because they controlled the distribution system, not because they controlled the technology.
I've done some work in reducing latency in telemetry systems. Some of it may be useful.
Buffering is the main problem. You have to look at the end-to-end system and find all of the places that data is being buffered. Examine hardware and software, add up all the bits and bytes of buffering.
Packet/frame size should be kept small. If it is too large, break it up into a sequence of smaller packets. Transmit four 128 byte packets instead of one 512 byte packet.
If possible, build the packet as it is being transmitted, a word at a time, rather than building a complete packet and transmitting it.
On the receiving side, you can process the data in a packet as it is being received, you don't have to wait for the last byte in the packet.
Error detection/correction hardware and software can add large amounts of latency.
Watch out for FIFOs in the transmitter and receiver. They can add substantial amounts of latency.
The ideal situation is to take a sample of a parameter and immediately put it on the wire. The receiver then processes the sample as soon as it receives the last bit of the sample.
A slower modem speed may actually reduce latency if it enables you to avoid the use of error correction. A dumb modem is the ideal.
A minor correction, ICMP is an integral part of IP. If you draw a diagram of a networking stack, IP and ICMP are at the same level, UDP and TCP are one level higher.
It isn't always that easy. In an infamous case, John Munden, a British police officer, was charged with attempted fraud and convicted for complaining about funds missing from his bank account. The bank, Halifax Building Society, said that their systems were secure, therefore Mr. Munden was lying. This was enough to convince the court. The conviction was later overturned on appeal.
Key storage and protection is an old problem. You have to assume that the operating system may be cracked, either by an external attacker or by an authorized user. The solution is to store keys in a tamper resistant hardware device, which can be an external box or a special chip. The keys can go into the device, but they can't come out. IBM has used this approach for their mainframe cryptographic facility for decades. IBM has a PCI card that solves this problem for PCs.
It has a lot to do with gun "control". In many places in the USA, the police will seize all firearms when they execute a search warrant, whether or not it is relevant to the warrant. They will refuse to return the firearms unless forced by a court order. Guns are "bad" so they feel justified in ignoring the Constitution and Bill of Rights. This sets a pattern for ignoring the law in other situations, such as the "War on Some Drugs". Similar abuses are seen when the Feds seize computers and hold them for years as possible evidence in prosecutions that may never happen.
In many countries the police rounded up the "usual suspects".
In the USA, the FBI did large numbers of interviews with the people on their lists.
Re:Conspiracy theorists want no need to believe.
on
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If you search the Microsoft Knowledge Base for leap year bugs, there are a fair number of leap year related bugs and glitches. Most of them don't look that bad. The Windows NT Server User Manager does not believe that 2000-02-29 is a valid date. This was fixed in SP4.
Every leap year, comp.risks seems to have a nice selection of leap year related bugs.
When I lived near the railroad tracks in Washington D.C., several kids became living (?) examples of Ohm's law when they decided to play on top of some railroad cars, directly underneath the 14 KV power lines that are used to power electric locomotives.
At my previous residence, elevator surfing was a popular fad until one of the little moppets made the fatal discovery that you shouldn't put your body in between the cab and the wall of the shaft.
Modern CPUs are high power, low voltage devices that need large numbers of power and ground pins. Each pin is limited to a relatively small amount of current. Many pins are needed for a high current, low impedance connection to the power supply.
That is not true for all computers. Many older and slower computers use BCD for dates and times. If you are programming an 8-bit microprocessor without hardware multiply/divide, it is easier and more efficient to use BCD. If you need to display or print the date/time, a BCD digit can be converted into an ASCII character with a single addition operation. BCD is also easier for humans who are examining hexadecimal core dumps and packet dumps. Serial time codes such as IRIG-B and NASA-36 are also in BCD format.
While I was happy to see 2000 arrive without any major incidents, I will feel better when my next paycheck is generated, hopefully without any errors. I keep thinking about the billions of lines of COBOL that are running on mainframes.
BCE and CE are used instead of BC and AD to avoid the religious connotations of Before Christ and Anno Domini. The year of our Lord is inappropriate/offensive if you are not a Christian. See http://www.radix.net/~dglenn/defs/ce.html for a discussion of the problem.
I have an old 68010 Unix development system with a release of SCCS (source code control system) that stops working as of 2000-01-01. All of the SCCS commands fail with fatal errors. The system is too old to be upgraded.
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If you assemble 8 bytes (with parity) into a 64 bit word, you can use SECDED (single error correct, double error detect) ECC on the 64 bit word. 8 check bits are needed for ECC on a 64 bit word.
I suspect that the television networks will have something to say about it. They may require their affiliates to carry the prime time network feed in high definition (1080i or 720p). NBC is not going to like competing against another network's high definition signal with a standard definition signal.
For anyone interested in the history of HDTV, I recommend the book "Defining Vision: The Battle for the Future of Television" by Joel Brinkley (ISBN 0-15-100087-5). It is an interesting account of how money and politics, not technical merit, were responsible for the creation of HDTV.
The original plan was to move all television stations to a smaller UHF band, freeing up the VHF channels and some of the UHF channels. It now looks like at least some of the VHF channels will remain allocated to television.
The FCC wants to auction off some of the recovered channels and reallocate some of the channels to other services, such as land mobile.
The television broadcasters would have lost even more spectrum without HDTV. A digital SDTV (standard definition) system would have greatly reduced their spectrum requirements.
The NAB (National Association of Broadcasters) was originally interested in HDTV as a means of protecting their spectrum allocations from other services (Motorola and land mobile). They needed to give the FCC a reason why it shouldn't reallocate large portions of the sparsely occupied UHF band to other services.
Let the cable subscriber's set top box or HDTV receiver decode the signal.
There is enough useless crap on my local cable system that there shouldn't be a problem with adding the HDTV signals from the local TV stations.
As a side effect of tracking down spammers and liquidating them, I found many low budget web sites that accepted credit card orders and stored them in globally readable files on the web server. If you read the source for these web pages, you can see how they process the data submitted by their customers. Many just take the data from the form and append it to a file on the web server.
One way to do this is to put a gatekeeper in between the order entry system and the secure database. The gatekeeper system is responsible for checking and forwarding all messages to/from the secure database. The gatekeeper has its own database of message types and message templates. Each incoming message is checked for a valid message type and the contents are compared to the message template for that message type. Only messages that pass all tests are forwarded. All others are logged and printed for analysis by the security office.
I read the article and I don't understand how the lack of free software is going to prevent anyone from creating and distributing video content. Sony will happily sell me a video camera, VTR and other expensive gadgets without any restrictions on content. The software vendors will also sell me encoding software and video server software without any restrictions on content. So what's the problem? The television networks had power because they controlled the distribution system, not because they controlled the technology.
Buffering is the main problem. You have to look at the end-to-end system and find all of the places that data is being buffered. Examine hardware and software, add up all the bits and bytes of buffering.
Packet/frame size should be kept small. If it is too large, break it up into a sequence of smaller packets. Transmit four 128 byte packets instead of one 512 byte packet.
If possible, build the packet as it is being transmitted, a word at a time, rather than building a complete packet and transmitting it.
On the receiving side, you can process the data in a packet as it is being received, you don't have to wait for the last byte in the packet.
Error detection/correction hardware and software can add large amounts of latency.
Watch out for FIFOs in the transmitter and receiver. They can add substantial amounts of latency.
The ideal situation is to take a sample of a parameter and immediately put it on the wire. The receiver then processes the sample as soon as it receives the last bit of the sample.
A slower modem speed may actually reduce latency if it enables you to avoid the use of error correction. A dumb modem is the ideal.
A minor correction, ICMP is an integral part of IP. If you draw a diagram of a networking stack, IP and ICMP are at the same level, UDP and TCP are one level higher.
It isn't always that easy. In an infamous case, John Munden, a British police officer, was charged with attempted fraud and convicted for complaining about funds missing from his bank account. The bank, Halifax Building Society, said that their systems were secure, therefore Mr. Munden was lying. This was enough to convince the court. The conviction was later overturned on appeal.
Key storage and protection is an old problem. You have to assume that the operating system may be cracked, either by an external attacker or by an authorized user. The solution is to store keys in a tamper resistant hardware device, which can be an external box or a special chip. The keys can go into the device, but they can't come out. IBM has used this approach for their mainframe cryptographic facility for decades. IBM has a PCI card that solves this problem for PCs.
It has a lot to do with gun "control". In many places in the USA, the police will seize all firearms when they execute a search warrant, whether or not it is relevant to the warrant. They will refuse to return the firearms unless forced by a court order. Guns are "bad" so they feel justified in ignoring the Constitution and Bill of Rights. This sets a pattern for ignoring the law in other situations, such as the "War on Some Drugs". Similar abuses are seen when the Feds seize computers and hold them for years as possible evidence in prosecutions that may never happen.
It was the Russian armed forces firing three Scud missiles at the Chechens. They said that anything under 500 km was unreportable.
In the USA, the FBI did large numbers of interviews with the people on their lists.
Every leap year, comp.risks seems to have a nice selection of leap year related bugs.
At my previous residence, elevator surfing was a popular fad until one of the little moppets made the fatal discovery that you shouldn't put your body in between the cab and the wall of the shaft.
Power distribution.
Modern CPUs are high power, low voltage devices that need large numbers of power and ground pins. Each pin is limited to a relatively small amount of current. Many pins are needed for a high current, low impedance connection to the power supply.
Would you please not post messages in monospaced font mode. While they look different, they are hard to read and cause eye strain.
That is not true for all computers. Many older and slower computers use BCD for dates and times. If you are programming an 8-bit microprocessor without hardware multiply/divide, it is easier and more efficient to use BCD. If you need to display or print the date/time, a BCD digit can be converted into an ASCII character with a single addition operation. BCD is also easier for humans who are examining hexadecimal core dumps and packet dumps. Serial time codes such as IRIG-B and NASA-36 are also in BCD format.
Happy 19100 :-)
There was no "unsigned long" data type, just char, int, unsigned and long.
BCE and CE are used instead of BC and AD to avoid the religious connotations of Before Christ and Anno Domini. The year of our Lord is inappropriate/offensive if you are not a Christian. See http://www.radix.net/~dglenn/defs/ce.html for a discussion of the problem.
Microsoft defines a long as 32-bits in Win64. They say they did this to make it easier to port Win32 programs to Win64.
I have an old 68010 Unix development system with a release of SCCS (source code control system) that stops working as of 2000-01-01. All of the SCCS commands fail with fatal errors. The system is too old to be upgraded.