The judgment of sentence is vacated and the case is remanded for further proceedings consistent with Commonwealth v. McCusker, -Pa. - (No. 2850 Allocatur Docket, Filed September 21, 1977). Upon remand the lower court must advise appellant as provided in Rule 1405(c), Pa.R.Crim.P. (added June 29, 1977, effective September 1, 1977); appellant should comply with the procedure set forth in Rule 321, Pa.R.Crim.P. See Commonwealth v. Marzik, 255 Pa. Super. -, 388 A.2d 340 (1978) (concurring opinion by SPAETH, J.).