Exhibit 99.1

         1.  Joint Filing.  Pursuant to Rule 13d-1(k)(1)(iii) of Regulation
13D-G of the General Rules and Regulations of the Securities and Exchange
Commission under the Securities Exchange Act of 1934, as amended, the
undersigned agrees that the statement to which this Exhibit is attached is filed
on behalf of each of them in the capacities set forth below.

         2.  Power of Attorney.  Know all persons by these presents that each
person whose signature appears below constitutes and appoints W. Robert Cotham,
William O. Reimann IV, Mark L. Hart, Jr., Thomas W. Briggs, and Calvin M.
Jackson, and each of them, as his true and lawful attorneys-in-fact and agents
with full power of substitution and resubstitution, for such person and in such
person's name, place and stead, in any and all capacities, to sign any and all
reports filed pursuant to Sections 13(d), 13(g) or 16(a) of the Securities
Exchange Act of 1934, filed on behalf of each of them with respect to their
beneficial ownership of CD Radio Inc., and any and all amendments thereto, and
to file the same, with all exhibits thereto and all documents in connection
therewith, with the Securities and Exchange Commission, granting unto said
attorneys-in-fact and agents, and each of them, full power and authority to do
and perform each and every act and thing requisite and necessary to be done in
and about the premises, as fully to all intents and purposes as such person
might or could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents or any of them, or such person or their substitute
or substitutes, may lawfully do or cause to be done by virtue hereof.


         DATED:    November 12, 1998



                        PRIME 66 PARTNERS, L.P.

                        
                        
                        By:  P-66, INC.,
                             general partner

                             By: /s/ William P. Hallman, Jr.                 
                                William P. Hallman, Jr., Vice-President 
                           

                        By:  P-66 GENPAR, L.P.,
                             general partner

                             By:  Carmel Land & Cattle Co.,      
                                  general partner

                                  
                                  By: /s/ William P. Hallman, Jr.           
                                     William P. Hallman, Jr., Vice-President 



                        COMPOSITE 66, L.P.

                        
                        
                        By:  P-66, INC.,
                             general partner

                             By: /s/ William P. Hallman, Jr.                
                                William P. Hallman, Jr., Vice-President 
                           

                        By:  P-66 GENPAR, L.P.,
                             general partner

                             By:  Carmel Land & Cattle Co.,      
                                  general partner

                                  
                                  By: /s/ William P. Hallman, Jr.           
                                     William P. Hallman, Jr., Vice-President