I had a passion for home brew digital audio recording, playback, and digital music creation.
How it works
Audio Byte was initially intended to be Playback of Digital Audio on the PC, a game developer library was also release.
Internal Speaker - 18,700 Khz 6 Bit, 36 db s/n quality better then phones or AM radio. The intent was to play back digital audio on a PC without having to add or modify any hardware. This was done using the Internal Speaker which is connected to a binary 0 to 5V TTL output from a timer chip. Up to this point it was only used to play simple flat beep that were just digital square waves at one frequency.
My code setup two timers to generate a fixed frequency square wave with a on to off width set by the second timer with a count from 0 to 63 or 6 Bits.
Any sample rate audio could be played back, because the code would use fixed point math to step though the sample, basically doing a crude sample rate conversion on the fly, within an interrupt routine. b Parallel Port - 44 Khz 8 Bit digital 48 db s/n (we've since tested it at over 1 Mhz to generate video!) Over 3000 were sold by Zebra Research. This works by plugging in a passive R-2R resistor network made of 50K Ohm and 100K Ohm resistors in to the printer port of the PC. The output was then connected to the auxillary input of a component stereo system or audio amplifier.
In addition 2 of the other signal pins where interconnected allowing the software to automatically detect what port if any the Audio Byte was connected to for playback.
Recording Adapter - 8 Bit 44 Khz This would take a headphone level input and sample it using the PC parallel port using a serial A/D converter from TI. This was using additional signaling pins as to not interfere the ablity to play back digital audio.
Challenges I ran into
Originally we called it Sound Byte, after selling it a flea markets for several months one customer trademarked the name and set us a cease and desist letter and release his product using our name!
This is why we changed the name to Audio Byte.
Accomplishments that I'm proud of
First Digital Audio for the PC We worked with Activision, Sony, Electronic Arts all of which used our libraries and supported our hardware.
What I learned
VC's suck. The VC were not interested in us while another funded Creative Labs that sold the Soundblaster. They sold 15x more units in their first month at 4x our price then we sold in our 6 year effort. It was much harder to install, it was less capable with less software support and lower quality audio. They did have full page ads in top maganizes and professional product distrubution.
What's next for Audio Byte
Still interesting for low end devices like Arduino maybe? Otherwise hopelessly obsolete.