Disk Sound Effects Board

General discussions related to the Altair 8800 Clone

Re: Disk Sound Effects Board

Postby Steve Hagins » February 25th, 2015, 9:03 am

This sounds like such fun!

My favorite Apple II emulator is Virtual II precisely because of all the wonderful disk and computer noises :)

If a whole other board would need to be created to support the disk sounds, please allow me to day-dream a bit.

1. Perhaps if the computer is communicating over the serial port at 110 cps, we could hear a paper punch machine?
2. If the computer is using the audio jacks maybe would could either hear the actual audio or even a simulation would be fun and educational. My younglings have a hard enough time with the cassette player itself ;)
3. An for the coup de gras, lifting the stop switch while toggling the right aux switch could play "Fool on the Hill"?
Maybe a fortunate owner of an original Altair could re-create this classic demonstration and record the goodness.

Probably a little silly in a thread where folks are longing for a real interface to a real floppy drive :P
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Re: Disk Sound Effects Board

Postby waltermixxx » July 3rd, 2015, 9:46 am

Just wondering if there was any more thought on sound effects?
i was watching Mike's videos on his disk controller card and the drives definately have a distinctive sound.
it would be cool to incorporate it some how... perhaps with a firmware upgrade? I wonder if there are any unused pins, ( I guess it would only be one pin?)
and room left on the micro controller to allow for the software for it :) :) or use two pins, one for sound and one for enable/dissable on aux 2? :)

Cheers.

I love my clone and I cannot wait to get my cassette interface so I can do the time-sharing basic, and load and save some cassette files. :)
Altair Clone, Briel 8800micro, Replica 1plus (wire wrapped), Cosmac Elf 2K.
I love this stuff, just wish my wife did... :)
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Re: Disk Sound Effects Board

Postby AltairClone » July 4th, 2015, 8:15 am

Unfortunately, I haven't had a chance to work on it all. It will have to be a small board with a processor like the cassette board. Maybe add Dave's audio amp to the board. The actual sound generation will be done by the additional processor based on simple digital commands from the main Altair board. No free I/O is available on the Altair board, but the HLDA LED is wired to the Altair processor and is never used - that output would be a good candidate for sound commands.

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Re: Disk Sound Effects Board

Postby Drunkle » July 7th, 2015, 7:35 pm

This little project has my interest. Time willing I might take a run at engineering a prototype and see where it goes.

Depending on the drive type being simulated, there would have to be four different types of sound effects. For example on the classic Altair Purtech 8 inch you would need to have:

1. The click made by the solenoid engaging the read/write head.
2. The whir of the drive motor spinning the disk media.
3. The tick-tick-tick of the track stepper moving the head from track to track.
4. The click (yes it sounds different) made when the read/write head solenoid disengages.

One thing that we need to remember is we would have a mix of drive whir and tick-tick-tick when the head movement sounds which would be normal in a real drive. Each drive sounds would have to be digital created or digitally sampled. The resulting sound files would then be put in to some form of non-volitional memory (SD card?) and sent to a CODEC (WTV020SD for example) for playback. Some from of interface system (PIC anyone?) would need to be setup to interpret what ever signalling setup between the clone and the sound generator system.

In the case of the sound files, I have the large-capsule condenser microphone and Pro-Tools HD studio to crate the high end digital source samples. I do NOT have the floppy drive setups to sample the sounds from.

My first thought for interfacing was to look at the INTE (pin 37 on U1) and the -CS lines on pin 1 of U4 & U5). Looks like all the CP/M read writes use the INT and your firmware access U4 & U5 for VDisk operations. Might be able to decode a pattern with the sound board processor.

Mike, if we use the HLDA line (pin 36 on U1) would you be willing to generate additional firmware code that would send a simple serial data stream for some type. Just for an example:

A long start pulse, shorter (half the start) pulses and a final long stop pulse. The sound board processor only has to count the half pulses between start and stop to find out what mode the drive would be in (start drive, step track or stop drive).

While looking at U1 on the main board, it looks like RG9 (pin 8), RD8 (pin 42), RD7 (pin 55) and RF0 (pin 58) are not visibly used. I will assume that they are all grounded under the chip?

Well that is my ramblings on the project. Any other thoughts out there?
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Re: Disk Sound Effects Board

Postby AltairClone » July 8th, 2015, 11:16 am

I've thought through this idea periodically over the last couple of years. The Altair drive motor runs all the time while a disk is inserted. Frankly, the drive cabinet's very loud fan runs all the time too. I think this steady noise is rather exhausting and probably not worth generating. However, head load, unload, and stepping would be great to hear since these sounds directly correspond to drive activity.

You are correct, head load is one sound, head unload is a different sound.

Multi-track stepping typically occurs at 10ms intervals. However, a complete single step sound clip, from start to end of decay, is longer than 10ms. My first experiment would be to see if just restarting the step sound clip each time a new step is issued sounds like a multi-step operation on the real drive. If so, that would make things much easier. It may require a "soft" end of the current clip that returns the waveform voltage to zero with a reasonable slope, and then restarts the sound clip, rather than just truncating the in-process sound clip.

The only easily accessible output remaining on the PIC is the HLDA signal. I can update the firmware to provide some sort of simple signalling on this pin to indicate head load, unload, and step.

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Re: Disk Sound Effects Board

Postby Drunkle » July 8th, 2015, 8:20 pm

Did not know that he spindle motor is always driving the media in the Altair 8 inch. I guess one would not leave a disk in he drive with closed door for long periods of time. But that does make it easier from a sound reproduction point of view.

So our tic-tic needs to be at a rate of 10mS or 100Hz. It would be nice to have a source digital sample that I could pass through Pro-Tools HD and look at the complex sound waveform. Could then create some test digital sound files with different tail decays and see how far we can push the 10mS sample block before it stops sounds like a stepper. If we are lucky the tic waveform would be leading peak sharp and already be many dB down at the end.

So do you have a nice microphone and boom stand over there to capture some test sounds? If not I can ship you one of my AT2020USB Cardioid Condensers and simple cheep boom mic stand that I use for field recording. You can just use any of the built in sound recording programs in Windows or Mac (or Linux if you use) to create the test sound samples. Grab some samples when ever you have time. There is NO rush from my end to sample sounds or return the equipment. Email/file transfer them to me. I'll then do my studio magic here and send you back some digital candidates for you to review. One thing though, it would be to not have any fan noise if possible.

Once we can prove the sound files we can look for one of the many sound CODECs chips out there. put the sample sound files in a prototype and see how it sounds. If this is all cool, finalize the digital interface and a board layout. I like the idea of making a integrated board with disk sound simulator, amp, input for Software Technology interface and com3/audio cassette interface. It would be nice to have just the audio connectors cassette and a volume/audio our for the other sound sources. Use the ideas of an infill panel in a serial hole with a 3.5mm and pot interconnected to the board?

In any case, if you are interested in teaming up, let me know via my email (which you should already have).
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Re: Disk Sound Effects Board

Postby AltairClone » July 8th, 2015, 8:57 pm

I have found that getting a good recording of head load, unload, and step while the drive motor and case fans are running is difficult.

Since no two drives sound exactly the same, there isn't a completely right or wrong set of sounds. I'm thinking the best thing to do is put on a Foley artist's cap and make up the sounds. It's amazing how many "normal" sounds in movies aren't actually real.

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Re: Disk Sound Effects Board

Postby Drunkle » July 8th, 2015, 10:18 pm

I thought of going that route also. I was planning to just grab some random solenoids and stepper motors/controller from my pile of random stuff here in the home lab. I have enough of them. Drag them in to the studio and have at it. What I was looking for is some reference drive sounds to analyze, then find some type of "Foley" stand ins. As far as mapping sounds for each type of sound that needs to be played, any sound effect that fits the timing of the sound loops would work. You could have a dog barking for the solenoid or gun shots for the track-to-track. ;)

For me I love playing with technology and designing things for the fun of it.
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Re: Disk Sound Effects Board

Postby sabea002 » December 26th, 2015, 11:22 pm

This sounds like an awesome project. I'm interested, are there any updates?
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Re: Disk Sound Effects Board

Postby AltairClone » January 6th, 2016, 6:49 pm

Nothing more done on this yet as far as I know. I still like the idea of it though!
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