The absolute ceiling for a high quality Type IV tape is probably around 600MB, assuming a dynamic range in the low 60s and low 20s frequency response - ie that

The absolute ceiling for a high quality Type IV tape is probably around 600MB, assuming a dynamic range in the low 60s and low 20s frequency response - ie that is how much it would take to sample losslessly. Though storing digital data losslessly is another story, it will be some fraction of that for forward error correction, but with sophisticated encoding you could probably get a few hundred megs on a high quality tape. A type I tape will be well under 100MB.