When a cellist wanted to present a solo program, there was a time when he had but two choices: either learn the fiendishly difficult J.S. Bach Suites for Unaccompanied Cello or hire an accompanist. In this computer age, all virtuoso cellist Eric Byers needed on Friday (Sept. 13) at Bread & Salt in Barrio Logan was his computer and an improvised sound system to make his musical compositions blossom.