Hacker Public Radio

Hacker Public Radio

Hacker Public Radio is an podcast that releases shows every weekday Monday through Friday. Our shows are produced by the community (you) and can be on any topic that are of interest to hackers and hobbyists.

Episodes

  1. 2 days ago

    HPR4720: Robert A. Heinlein: Earlier Novels

    This show has been flagged as Clean by the host. Heinlein published his first novel in 1948, and within a decade had published some major works. What distinguishes these early novels from his later ones is that he has not pushed the boundary of what he can write about to the degree he does in the 1960s and later. But there are fine novels in this period. Heinlein’s Earlier Novels During the 1950s Heinlein was busy with his Juvenile series, but also found time to write some adult novels, and some of them are very good. A few of them were expansions of earlier, shorter works that he turned into full novels. Beyond This Horizon (1948) – This is Heinlein’s first novel after the lackluster For Us The Living (which never was published during his lifetime; Heinlein knew it was sub-par). It is set in a future society that is practicing a form of eugenics, with a breeding program designed to produce the perfect human by selecting for health, longevity, and intelligence. The protagonist, Hamilton Felix, is not the one, but he is near to the end. And this society has also made it a point to keep a certain number of people who are not part of the breeding program, as a form control for the experiment. Hamilton Felix is in fact the penultimate step in this program, but has so far shown no interest in marriage or procreation. But in the course of the novel he is persuaded. His children are shown to be the end point of the program at the end of the novel. A sub-plot involves his friend Mordan Claude (in this book everyone puts their family name first) who falls for a woman he meets. When she sneezes, he begins to suspect she is one of the “control naturals”. They are protected, but clearly this is a class society, which is to be expected in any society that practices eugenics, and should be off-limits for Claude. But love conquers all, and then he discovers that she is not a control natural after all, which to my mind is a somewhat weaker outcome.Another aspect of this society is that most people are armed, and dueling is common. This is explained as “An armed society is a polite society,” since if you offended someone you could find yourself in a duel very quickly. A lot of gun enthusiasts have picked up on this and repeated it as if it was revealed truth, but even a cursory examination of societies with a lot of guns shows it to be false. Sixth Column (1949) – This novel was originally a serial written in 1941, when the Sino-Japanese war was in full swing, and this motivates some of the ideas in this book. The setting is a United States that has been conquered by the Pan-Asian Federation. This Federation had previously absorbed the Soviet Union and India, and is portrayed in very much Yellow Peril manner. John W. Campbell had a lot to do with this, and it makes the novel something that you can skip without losing much. The Pan-Asians regard the Americans as slaves. And their policy towards their slaves is “Three things only do slaves require: work, food, and their religion.” In an American military outpost hidden in the mountains of Colorado a miracle weapon is found that can kill, and it can somehow be tuned to only affect the Asians and not the Americans. Since the Pan-Asians have allowed religion (better to pacify the slaves), the Americans create a religion and use that to infiltrate the Pan-Asian facilities. Heinlein himself had a low opinion of this novel, and deservedly so. The Puppet Masters (1951) – This novel is a product of the paranoia of the times regarding Communists. But this novel is more of an allegory than a direct anti-Communist screed. It is fundamentally about “the enemy within”, in the form of alien parasites called slugs that can take over a human by controlling the nervous system, making the human a powerless slave to the alien. And they are attempting to conquer the world, though all of the action we see takes place in the United States. This is essentially The Body Snatchers plot, and has been done many times. But both this novel and the previous Sixth Column reflect the feeling of paranoia prevalent in society when people thought there were communists under every bed looking to corrupt the youth and subvert The American Way of Life. And it is notable that the organization that leads the fight against the slugs is a top secret outfit established without the knowledge of Congress and responsible only to the President. Double Star (1956) – This is when Heinlein as a novelist starts to really click, and it was shown by his winning his first Hugo for best novel. The plot is somewhat reminiscent of Prisoner of Zenda. In a future solar system, Earth, Venus, Mars, and the Jovian satellites are united under a parliamentary democracy, which is in turn under a constitutional monarchy. Think of it as similar to the UK, only in this case it is the House of Orange that are the monarchs. A politician named John Joseph Bonforte is the leader of the Expansionist coalition, and one of the most prominent politicians in the solar system. And he has been kidnapped sat a crucial time. His staff find an actor, stage name The Great Lorenzo, who is similar enough physically to impersonate Bonforte, while they try to get the real Bonforte back. They do succeed, but he has been very badly treated by the kidnappers, so the actor has to continue for the election campaign. And he wins the election, but the real Bonforte dies. The actor then continues to impersonate him to the point of really becoming him. The two things that make this novel so interesting are first, the focus on acting as seen through the eyes of Lorenzo; and second, the focus on the machinery of politics. And this draws upon Heinlein’s own experience in electoral politics. Though he was not successful in getting elected, he clearly had absorbed a lot about the how-to of the process. And he did write a non-fiction book called Take Back Your Government (1992), which was published posthumously. It was subtitled A Practical Handbook for the Private Citizen Who Wants Democracy to Work, and was originally written in 1946. It was based on his experience with EPIC and in trying to get Upton Sinclair elected Governor of California in 1934. The Door Into Summer (1957) – This is another good novel, which features several themes that would reappear through Heinlein’s work. The first is that Heinlein was a very confirmed cat lover. The title comes from a cat who went from door to door in the middle of winter, trying to find the door into summer. Second, the protagonist is an engineer, which is of course Heinlein’s background. The third is the time travel element. People can travel into the future through a type of suspended animation called Cold Sleep. But for the purposes of the plot a scientist has invented a time travel device that sort of works. It sent a grad student named Leonard Vincent a few centuries back in to Italy where he became Leonardo da Vinci. But it sends our hero, Daniel Boone Davis, back exactly where he wanted to go. We see a few things in this novel that are of interest. First, the cat, Pete, has the full name of “Petronius the Arbiter”, who was the author of the Satyricon, so Heinlein’s interest in sex is starting to make an oblique appearance. Second, when Dan goes back in time, he lands in the middle of a nudist camp, and that is also something Heinlein was very interested in.The plot can be summarized as Dan gets robbed of his inventions by his business partner and his secretary/fianceé, gets put into Cold Sleep, then goes back in time to just before he got robbed and fixes things to his satisfaction, then takes the Cold Sleep again to finish his plans. It is a pretty good yarn. Methusaleh’s Children (1958) – This was originally a novella written in 1941, then expanded into a novel. It is part of the Future history. It introduces Lazarus Long, who would go on to be Heinlein’s alter ego through many of his future books, and thus implicitly makes those books part of the Future History, though most scholars will dispute this. What cannot be disputed is that this novel is a cornerstone for where Heinlein would go in many of his future stories.The story begins with a successful businessman named Ira Howard who dies of old age at around the age of 49 in the 19th century. In his will he leaves his estate to trustees with the mandate to find a way to extend human life span. The best they can come up with is to encourage (financially) people who had long-lived grandparents to marry each other and have children. They carry this on and by the 22nd century the Howard Families, as they call themselves, have an average life span of 150 years. But they have to hide this form the rest of society, and arrange from time to time to “die” and then become someone else. This masquerade helped them survive the years of Nehemiah Scudder and his successors, but a few of them reveal themselves during the Covenant government. This has a bad result because people want the secret that they assume the Howard families are hiding, and they might be willing to kill to get the secret. So the Howard families steal a starship and make their escape. One of the people onboard is Andrew Jackson “Slipstick” Libby, who we first met in the short story Misfit, and he manages to come up with a Faster-Than-Light drive. They finally decide to go back to Earth, where they discover that scientists have found ways to prolong human life and they are no longer enemies, in fact they are welcomed for bringing the FTL drive.This is definitely a must-read novel for anyone who wants to get into the Heinlein universe. So many other works are based on it. Links https://en.wikipedia.org/wiki/Beyond_This_Horizon https://en.wikipedia.org/wiki/Sixth_Column https://en.wikipedia.org/wiki/The_Puppet_Masters https://en.wikipedia.org/wiki/Double_Star https://en.wikipedia.org/wiki/Take_Back_Your_Government https://en.wikipedia.org/wiki

  2. 4 days ago

    HPR4718: Programmable Logic Controls - Episode 2

    This show has been flagged as Clean by the host. -------------------- 01 Introduction This is the second episode in an 8 part series. 02 In the previous episode we discussed the predecessors of PLCs, in particular relay logic. In this episode we will discuss how relay logic came to be expressed in software rather than in actual hardware components. 03 The topics to be covered include * Early computers in industry. * The first PLC. * PC versus PLC - what's in a name. * Who the major brands are. * What does a PLC actually look like. * Machine architecture. * PLC programs. * The scan. * PLC programming languages. * Relative popularity of PLC programming languages versus more conventional computer programming languages. -------------------- 04 Early Computers in Industry Computers came to be used in industry fairly early on. Minicomputers were used in some large industries to control things like electric power plants. For example, the DEC PDP8 was used to control the refuelling machines in CANDU nuclear power plants. These would load and unload fuel from the reactor, which happens continually on a daily basis while the reactor is running. 05 The first microprocessor based computer sold on the commercial market was the MICRAL from France, based on the Intel 8008. It was sold as a cost effective replacement for minicomputers used in industry. It preceded what are generally considered to be the first Personal Computers. So you can see that industry were not reluctant to adopt new technology. 06 However, mini computers were large complex systems that did not fit well into a factory floor. They had particular niches in very large complex integrated systems, but were not suited to controlling many individual machines in a factory that produced things like automobiles or appliances. 07 What was needed was something that would fit into a standard electrical enclosure, withstand the temperatures found in a factory, could stand up to vibration and noise, was tolerant of voltage fluctuations, interfaced directly to sensors and actuators, and could be readily programmed by engineers, technicians, and tradesmen who were familiar with the processes to be controlled, but had little or no experience with computers. 08 This required a complete integrated package covering hardware, software, and product distribution through industrial supply retailers. Something that could meet these criteria is what was needed to become the PLC. -------------------- 09 History Many histories point to a US developer that became Modicon. However, their first hardware was more a proof of concept than a viable commercial product. In fact multiple companies in the US, Europe, and Japan were working on the problem and released comparable products all at around the same time in the early 1970s. 10 The idea preceded the implementation by a number of years. For example, General Motors had asked industrial control equipment suppliers in the mid 1960s for some sort of programmable control device to replace relay logic. This showed potential suppliers that there was a market for this sort of thing, and gave them a clearer idea of what customers were looking for. 11 What made this possible was the development of the first 8 bit microprocessor in that time period, combined with readily available bit slice processors from the minicomputer industry and other components. 12 People knew what to do, the problem was waiting for the development of suitable component hardware. Minicomputers were already being used in industry, but were normally located in control rooms. PLCs were an effort to take that technology out of control rooms and put it on the shop floor. 13 PC Versus PLC - What's in a Name In the early days, these systems were known as either PLC, which means "Programmable Logic Controller", or PC, which means "Programmable Controller". Different vendors favoured different terminology, but both were common. I have a book which was at one time one of the standard reference handbooks for this industry which was published in 1989, and refers to them as Programmable Controllers, or PCs. 14 The term PC was also used to mean "Personal Computer", but that wasn't really a problem in the early days. However, a certain large company decided to call their entry into the personal computer market the "IBM PC", and suddenly "PC" became a generic term for desktop computers. 15 After a long struggle to keep referring to their products as "PCs", even the biggest vendors caved in and gave up the fight and switched to using the "PLC" term. I will therefore use the term "PLC" in this podcast series even when talking about products which were originally called "PCs" at the time they were introduced. 16 Who the Major Brands Are The companies that came to dominate the industry fairly early on were generally companies that already made industrial electrical hardware. These were Siemens Allen Bradley, later known as Rockwell Schneider Mitsubishi Omron 17 These are still the dominant companies in the business, although there are many small brands, particularly at the cheaper end of the market. All of them were suppliers of a wide range of industrial control hardware, such that you could build all or nearly all of the parts of your control system using only their products. 18 Each of these sells an integrated hardware and software package, including development software, that is completely proprietary. If you thought that the mainframe business had a lot of vendor lock-in, you haven't seen the industrial market. -------------------- 19 What Does One of These Things Actually Look Like? At this point you are probably still very confused as to what a PLC actually is. I will attempt to describe one in basic terms by giving an example of one. The smallest and simplest ones are what are termed "shoebox" PLCs. These are basically a rectangular box with a plastic case. 20 Here are the dimensions for a typical low end model, a Mitsubishi FX3U-32M. According to specs in the manual, it is 150mm wide, 90mm high, and 86mm deep. 21 It can be mounted to the panel in an electrical enclosure by snapping it onto what is termed a DIN rail. DIN rails are standard mounting systems which use a strip of metal which is U shaped with a lip at the top of each end of the U. You screw the DIN rail to the electrical panel in the enclosure, and most industrial components such as PLCs, terminal blocks, circuit breakers, and all sorts of other things will simply snap onto it and be ready to wire together. 22 Along the top and bottom of the PLC are terminals to which you can attach wires from the things you want to sense or control in the rest of the machine, such as push buttons, pilot lights, proximity sensors, and valves. 23 Inputs are along the top, and outputs are along the bottom. The FX3U-32M has 16 inputs and 16 outputs. These I/O can be 24 volts DC, or 100 to 120 volts AC, depending on the model. Alternatively it may have small relays for outputs. While AC I/O once predominated, 24VDC became the standard in most industries several decades ago as it interfaced with electronic devices more readily and also allowed for cheaper and more compact wiring. 24 More inputs and outputs can be added by connecting additional I/O modules to the main PLC next to it on the same DIN rail, up to a total of 256 I/O The connection is typically via short ribbon cables which plug into the adjacent module. These I/O modules look like the main PLC, but just add I/O. 25 Inside the PLC are a CPU, memory, and firmware. This model has 64K "steps" of memory, which can be thought of as how many instructions you can have. The program runs in RAM, but you can add a small flash memory device to save the program to. There is a run/stop switch that allows you to start or stop the user program. There is a port that you can use to connect the PLC to a laptop computer with a cable so you can download your program to it. 26 The biggest part of the market for PLCs is for these "shoebox" style. However, there are bigger ones as well which have more I/O, more memory, faster CPUs, etc. These are meant for tasks such as coordinating large assembly lines and things like that. These are what are termed rack systems, where the rack is an empty box which is open at the front and has a backplane bus running along the back. You plug the main CPU into the bus, normally in the leftmost position, and then plug I/O modules into the rack. The I/O modules are tall, thin, fully enclosed boxes with the I/O terminals along the front. 27 You should have a rough idea of their appearance at this stage, so I'll leave the physical description aside for now and go on to the concepts behind how they actually work and what makes them different from something like say a Raspberry Pi. -------------------- 28 Machine Architecture It is not really the hardware which defines the PLC. Rather, it is the software system architecture. Every PLC that I am aware of has a common set of features. 29 Data Table A data table is simply a block of memory which may or may not be subdivided into different parts. All logic, and all, or nearly all, I/O works by writing to and reading from addresses in the data table. 30 I/O Every input and output point maps to a fixed memory address in the PLC. To read the state of an

  3. 5 days ago

    HPR4717: Visit with a blind Ham operator

    This show has been flagged as Clean by the host. Hi, this is Archer72 for another episode of Hacker Public Radio. In this episode, it is my first experience troubleshooting with an experienced blind Ham operator who is located 20 miles away from my hometown. When traveling there, I could not miss his house, which was the only one off the main road with an estimated 50 foot antenna. That’s 15 meters for the rest of the world. This antenna was intended for the HF high frequency band, for which the local Ham radio club had very recently extended to this height. The target radio bands are 20, 40 and 80 meters. I had missed a great opportunity to record the session so wanted record (and write this) while it was fresh on my mind. Several months later… This particualar operator (KG4QWH) (Kilo-Golf-Four-Quebec-Whiskey-Hotel) was a radio operator for the local emergency services for 22 years, after which the new company decided to cut back on staff. A local broadcast radio station was hiring soon after and was using some version of Linux which was not accessible for a blind user like himself. This conversation was started after I was asked about his computer that he was trying to force update on older hardware from Windows (7?) to Windows 11, in true hacker fashion. While talking about the Linux situation and also the Windows side, it brough to light the glaring (near) ommision of accessibility software in both camps. On the Windows side, which is more familiar to my friend, is Jaws. Great software, but year after year the barrier of cost is getting more, and on the Linux side accessibility is not looking any better. While cost is not a factor in using it, and this is only coming from me, the voices could be better. Piper is an option for natural sounding voices, but has yet to be integrated into a FOSS screen reader AFAIK. On the positive side of accessibility, the Kenwood radio (model TS-590S) has the option to add a module to give an audible description of the buttons being pressed, and at the time there was gnother operator who came through and talk him through some receiver settings. The reason I went there is the first place was that the Kenwood microphone was causing noise to come across the speaker when he keyed up the mic. Initially the proprosed solution was to switch two wires inside the Kenwood microphone. I was asked about this ahead of time so was prepared with an electrical box with miscellaneous low voltage wires and stripping tool, also a Pincil soldering iron equiped with a USB C 100 watt power supply. To fix the problem on the Kenwood MC-60 microphone, you need to swap the wires so that mic hi is on Pin 1 and mic low (shield) is on Pin 7. This is often necessary due to factory wiring errors. After finding out that the proposed solution was to open the mic, which required a heat gun the soften the locktight, I tried another route. My friend had a toroid choke handy, and I coiled the feed line to the back of the radio around the toroid. (8 - 10 times?) This had no effect. Next to try was to ground the mic from the outside, which there was a bare metal screw on. This connected to a dedicated ground on the back of the Kenwood TS-590S radio. This seem to suppress the hum when using PTT. The rest of the evening (the best time for HF), Matthew was able to make contacts on 40 meters. Great to meet you as well my friend and I appreciate you coming up. I was able to talk on 40 this evening with no problems. I reached several in Kentucky Indiana and I even reached Kansas. Come to think of it. I was even able to reach someone on the Jersey shore. References Blind Hams Network New CQ Blind Hams Podcast: CQBH 011 TS-590SG Tutorial by N3AIN New CQ Blind Hams Podcast: CQBH 012 TS-590SG tutorial by N3AIN KENWOOD TS-590S instruction manual KENWOOD VGS-1 instruction manual KENWOOD Communications Microphone MC-60A Instruction Manual Image of a 15 meter HF antenna on a two story house in Kentucky. Provide feedback on this episode.

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Hacker Public Radio is an podcast that releases shows every weekday Monday through Friday. Our shows are produced by the community (you) and can be on any topic that are of interest to hackers and hobbyists.

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