Classic Computer Magazine Archive COMPUTE! ISSUE 32 / JANUARY 1983 / PAGE 10

Can Atari Make Tapes For Other Computers?

It is my understanding that the programmable tone generators in Atari also generate the baud rate and tones used for cassette recording. If this is so, it should be possible to save programs in Kansas City Standard or other two tone formats, making possible the use of Atari editing features to prepare cassette tapes for other computers. How can this be actually done?

Steven S. Coles

While the Kansas City standard cassette interface is in use by many computers, it should be noted that it is far from a full standard. Most computers deviate from the original standard one way or another. One nearly universal deviation is to operate at 1200 baud rather than the original 300 baud spec.

The Kansas City standard uses a frequency of 1200 Hz to indicate a "0" bit and a frequency of 2400 Hz to indicate a "1" bit. The frequency change is performed when the waveform crosses the zero voltage level. The actual data transfer is usually done through as USART, but it is quite possible to simulate this in software. At this point we run into a brick wall: just about everybody saves the data on the cassette in their own way, so you will have to find out what method is used for the computer you wish to adapt to. If at this point you are still interested in giving it a go, I suggest you go down to your local library and drag out the April 1977 issue of BYTE. On page 40 you will find an excellent article by Carl Helmers on how to do it.