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OK, so back before ice age, I recall having a Sinclair ZX80 PC (with TV as a display, and a cassette tape player as storage device).
Obviously, the programs on cassette tapes made a very distinct sound (er... noise) when playing the tape... I was wondering if someone still had those tapes?
The reason (and the reason this Q is programming related) is that IIRC different languages made somewhat different pitched noises, but I would like to run the tape and listen myself to confirm if that was really the case...
I have the tapes but they've been stored in the garage at my parents' house and the last thirty years hasn't been kind to them.
You can get images here though: http://www.zx81.nl/dload if that's any use. Perhaps there is a tool out there for converting from the bytes back to the audio ;)
Edit: Perhaps here: http://ldesoras.free.fr/prod.html#src_ay3hacking
On the ZX80, ZX81 and ZX Spectrum, tape output is achieved by the CPU toggling the output line level between a high state and a low state. Input is achieved by having the CPU watch an input line level. The very low level of operation was one of Sir Clive's cost-saving measures; rival machines like the BBC Micro had dedicated hardware for serialisation and deserialisation of data, so the CPU would just say "output 0xfe" and then the hardware would make the relevant noises and raise an interrupt when it was ready for the next byte. The BBC Micro specifically implements the Kansas City Standard, whereas the Sinclair machines in every instance use whatever adhoc format best fitted the constraints of the machine.
The effect of that is that while almost every other machine that uses tape has tape output that sounds much the same from one program to the next by necessity, programs on a Sinclair machine could choose to use whatever encoding they wanted, which is the principle around which a thousand speed loaders were written. It's therefore not impossible that different programs would output distinctively different sounds. Some even used the symmetry between the tape input and output to do crude digital sampling, editing and playback, though they were never more than novelties for obvious reasons.
That being said, the base units of the ZX80 and ZX81 contained just 1kb RAM so it's quite likely that programmers would just use the ROM routines for reading and writing data, due to space constraints if nothing else. Then the sound differences would just be on account of characteristic data, as suggested by slugster.
I know these come up on auction sites like Ebay quite frequently - if you want to buy them yourself. If you get someone else who owns one to listen then you are going to get their subjective opinion :)
In any case, the language used to save it would be the secondary cause of the pitch changes - it will be related to the data. IOW you could probably create a straight binary data file that sounded very similar to a BASIC program (the BASIC would have been saved as text, as it is interpreted).
I know the threads old but... I was playing about with something similar last night and I've got a wav of an old zx81 game if you're still interested? pm me and I'll post it somewhere.
You can use something like http://www.wintzx.fr/ or pick something from http://www.worldofspectrum.org/utilities.html#tzxtools to convert an emulator file to an audio file and then you can just play it on your PC. Some tools also allow you to play the file directly. Emulator files can be found at http://www.zx81.nl/files.html and many other places.
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This question does not really relate to any programming language specifically, it relates to, I think, EVERY programming language out there.
So, the developer enters code into an IDE or something of the sort. The IDE turns that, directly or indirectly (maybe there's many steps involved: A turns it into B turns it into C turns it into D, etc.), into a machine language (which is just a bunch of numbers). How is machine language interpreted and run? I mean, doesn't code have to come down to some mechanical thing in the end, or how would it be run? If chips run the code, what runs the chips? And what runs that? And what runs that? On and on and on.
There is nothing really mechanical about it - the way a computer works is electrical.
This is not complete description - that would take a book. But it is the basis of how it works.
The basis of the whole thing is the diode and the transistor. A diode or transistor is made from a piece of silicon with some impurities that can be made to conduct electricity sometimes. A diode only allows electricity to flow in one direction and a transistor only allows electricitry to flow in one direction with an amount proportional to the electricity provided at the "base". So a transistor acts like a switch but it is turned on and off using electricity instead of something mechanical.
So when a computer loads a byte from memory, it does so by turning on individual wires for each bit of the address address and the memory chip turns on the wires for each data bit depending on the value stored in the location designated by those address wires.
When a computer loads bytes containing an instruction, it then decodes the instruction by turning on individual wires that control to other parts of the CPU:
If the instruction is arithmetic then one wire may determine which registers are connected to the arithmetic logic unit (ALU) while other wires determine whether the ALU adds or subtracts and another may determines whether it shifts left or does not shift left.
If the instruction is a store then the wires that get turned on are the address lines, the wire that determine which register is attached to the data lines, and the line that tells the memory to store the value.
The way these individual wires are turned on and off is via this huge collection of diodes and transistors, but to make designing circuits manageable these groups of diodes and transistors are clumped into groups that are standardized components: logic gates like AND, OR and NOT gates. These logic gates have one or two wires coming in and one coming out with a bunch of diodes and transistors inside. Here is an electrical schematic for how all the diodes and transistors can be wired up to make an OR gate: http://www.interfacebus.com/exclusive-or-gate-internal-schematic.png
Then when you have the abstraction level of logic gates it is a much more manageable job to design a CPU. Here is an example of someone who built a CPU using just a bunch of logic gate chips: http://cpuville.com
Turns out there is already a book! I just found a book (and accompanying website with videos and course materials) for how to make a computer from scratch. Have a look at this: http://nand2tetris.org/
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I am looking to create a music creation application, and would like to allow the user to play the individual notes of an instrument. Is there a place online where I can find individual sound files that I may playback for each note, or is there a way of programmatically "generating" each pitch? I am not concerned with sound quality at this point in my development.
EDIT: I am still in the early stages of development. I want the app to be browser based, using Javascript or something similar. A Linux development environment, if that is of relevance at all. The notes will be played via an on-screen interface.
The University of Iowa's Electronic Music Studios has a very nice and complete archive of sampled instruments, with one musical note per file. You should also check out freesound, though that is a much more general-purpose sample sharing site.
There are plenty of places online to find sampled instruments. If you're not concerned about sound quality, some free soundfonts will most likely do the job.
For example, this site http://soundfonts.homemusician.net/ has pianos, basses, guitars, horn etc. (Google "free sf2" for more)
There are plenty of ways to generate (aka synthesise) tones as well.
If you don't mind MIDI files, you can get a free MIDI software piano and create your own files: C.mid, C#.mid, D.mid, etc.
Here's one with a quirky interface but there are many more:
http://download.cnet.com/MidiPiano/3000-2133_4-10542342.html
The easiest way to do this is to simply output MIDI messages to the synth built-in to every computer. No need to create MIDI files or use extra sound fonts.
You didn't mention what language you are using, so it is hard to suggest ways to get started. In all cases though, you'll want to read up a bit on what MIDI actually is.
Basically, MIDI is nothing but control data, commonly used with synthesizers. At a basic level, there are note-on, and note-off messages. There are many other kinds of messages too, such as pitch bend, control change, etc. MIDI supports 16 "channels", which are sent all down the same line, just with a different identifier.
A good utility (on Windows) for debugging MIDI messages (and getting a better idea of the protocol in general!) can be found here: http://www.midiox.com/
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I´ve a question according sensor programming. I´m searching a sensor that tells me, for example, if a glass of water is more than half full. I´ve already googled that, but I can´t find anything.
So my questions are:
Where can I buy such a sensor?
What programming language do I need to control such a sensor?
Thanks for answers..
Update from comments below one of the answers
What I really need it for is a big container, in which is some corn. I
want to use the sensor to tell me, just as the corn is under a defined
point of the container. So that I can calculate, at which time I have
to refill the container.
Your sensor could be a level sensor. There are several principles on which level sensors work (see here). Some of them will work with granular solid material. (For example, an ultrasonic range sensor could shoot a pulse at the surface of corn mass, detect the reflection, measure round trip time of flight.)
... or it could be a proximity sensor, as somebody had suggested above.
... or it could be a weight sensor. Here's an application note on weighing vessels.
If you google "level sensor for grains", you may find something useful.
What language to use would depend on what you will connect connect the sensor to. If it will be connected to a microcontroller, the language would be C. If it will be connected to a PC, then it would depend a lot on the particular model of the sensor.
By the way, here's a web group dedicated to sensors.
I would imagine you could use a similar mechanism to a car's fuel tank. Have a mechanism that stays afloat in the container with an attached arm and a magnet on it, then using a Hall sensor you can observe the change in hall reading as the floating part rises or falls within the container.
"What I really need it for is a big container, in which is some corn."
Perhaps one of those sensors that are used to ensure garage entry ways are clear before an automatic garage door is allowed to close. It uses an optical beam of light.
Do you know the size of the glass in question? You could just get a scale and work out how heavy the glass would be when it is half full of water. My guess is that you could probably find a sensor that could do this and it would most likely need to be written in C.
This guy seems to be having the same problems:
http://forums.makezine.com/comments.php?DiscussionID=6052
Good luck.
Also check out Arduino for micro controller electronics.
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let's consider a variation of the "WAV to MIDI" conversion problem. I'm aware of the complexity of such a problem and I know that a vast literature about the more general Music Information Retrieval (MIR) subject exists.
But let's suppose here that we already have both the WAV and the MIDI representation of a music piece, so we actually don't have to discover pitches inside the WAV signal from scatch... we "just" have to match the pitches detected (using a suitable algorithm) with the NoteOn events contained in the MIDI representation. I definitely suppose we should use the information contained in the MIDI file to give some hints to the pitch detection algorithm.
Such a matching tool could be very useful, for example for MIDI "humanization": we could make the MIDI representation more expressive using the information retrieved from the WAV signal to "fine tune" note onsets, durations, dynamics, etc...
Does anybody know if such a problem has already been addressed in literature?
Any form of contribution or assistance will be greatly appreciated.
Thanks in advance.
At the 2010 Music Hackday in London some people used the MATCH Vamp plugin to align score to Youtube videos. It was very impressive! Maybe their source code could be of use. I don't know how well MATCH works on audio generated from MIDI files, but that could be worth a try. Here's a link: http://wiki.musichackday.org/index.php?title=Auto_Score_Tubing
This guy appears to have done something similar: http://www.musanim.com/wavalign/ His results are definitely interesting.
This seems like an interesting idea. What are you trying to do, is it just match the notes pitch? Or do you have something else in mind?
One possible thing that you could look into is if you know the note (as an integer value I think its been a while) that will be used to pass into the noteOn method, you may be able to do something with that to map it with a wav signal. IT depends on what you are trying to do.
Also, there are some things that you could also play around with in (I think it is called) the midi controller. Such as: modulation, pitch, volume, pan, or play a couple of notes simultaneously. What you could do with this though, is have a background thread that can change some of those effects as the note is being played. For example, you could have a note get quieter the longer it is played, or have a note that with pan between the left and right speakers, etc
I havnt really played with this code in a long time, but there are some examples of using a midi controller.
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I've done a google search of this topic, but so far haven't found anything satisfactory.
From your experience, what's the best place to get game resources, like sprites, backgrounds, sound effects, music, etc.? To be more specific, I'm looking for more of sound effects and music, which I'm currently lacking more than graphics. However, for graphics, I've tried getting random graphics from different sites, but they just don't match. I don't want to copy one entire graphics package either.
The resources should be free and easy to obtain. The products I intend to make are free if not open source, and are unlikely to receive widespread attention or produce profit for myself, so I'd like something that I can use and distribute freely.
I don't have enough graphics and musical knowledge to attempt to create resources from scratch and don't know anyone willing to do so.
I'm working with Java. I'm sure I can read all kinds of file formats with it, or if not, I can always use software to convert resources.
In terms of graphics, Daniel Cook of Lost Garden produces some seriously high quality, reusable game art that is free for both personal and commercial work (read his license details). Here's the index of his free graphics related posts, just hit the "read more" link at the bottom of an article and you'll find links to the downloads.
edit: in terms of sound effects, Soundrangers is pretty decent if you have something specific in mind, but it can quickly get expensive. For a complex game, if you're wanting a rich user experience you'll need dozens, if not hundreds of sound effects. At a couple of bucks a pop, that adds up real quick. A lot of places (including Soundrangers) offer thematic sound packs which give you a little more bang for your buck, but it's still not free. GameDev also has a listing of audio resources.
For music, I think your options are better. Depending on what kind of thing you're looking for (ambient, instrumental, vocal etc). I would seriously think about approaching local independent musicians and using existing tracks that they have. They're likely to let you use their music for free (properly accredited of course) or at a reasonable cost.
There's http://www.freesound.org/
Most stuff there has a license that is incompatible with, say, Fedora, for instance, though if you ask the copyright holder sometimes they'll license things under a different license.
Music is harder to come by than sound effects. you could try digging around on archive.org, say here: http://www.archive.org/details/muzic
Also check out sfxr http://www.cyd.liu.se/~tompe573/hp/project_sfxr.html
though the sounds that it makes are pretty old school sounding -- and if that's what you're looking for, it's cool, otherwise, it can make some place holder sound effects.
If you're looking for interesting textures, I would suggest checking out Filter Forge. You can download the filters for use in Adobe Photoshop, or you can potentially use the sample images on the site to create texture maps for various types of terrains and materials.
GarageGames.com sells a lot of that kind of thing... 3d models, textures, background music and so on.
http://garagegames.com and specifically http://www.garagegames.com/products/browse
HTH
edit: whoops, I didn't see the "free" requirement! Do a search on "creative commons" and you'll find lots of music, at least, and some graphics.
Don't know if this is the type of thing you're looking for, but Game Sprite Archives has a huge huge collection of SNES/NES/Anything pre-playstation 1 sprite rips.
I just discovered this site the other day while looking for some sound effects:
http://www.soundrangers.com/
It looks like they're royalty-free but most of the sounds cost a buck or two. Looks like some sounds are free though.
Clipart
Open Clip Art
Textures
ImageAfter
CG Textures
OpenFootage
Texture Hound
I recommend Sound Snap, they allow 5 free downloads for a month for the free accounts, and more if you sign up. I have been using them for the past couple of months for the games I have developed.