Complex sentence: The TOI computer failed to materialize, mostly due to the fact that it required an 80-column character display which in turn required the MOS Technology 6564 chip, which could not be used since it required very expensive static RAM to operate fast enough.
Split into simpler sentences: The TOI computer failed to materialize, mostly due to the fact that it required an 80-column character display which in turn required the MOS Technology 6564 chip. However, the chip could not be used in the TOI since it required very expensive static RAM to operate fast enough.