Вариант от Busy:

runusr res 4,(iy+#01) ;; Switch to 48 basic
ld hl,(ramtop) ;; Recontruction of stack for 48 basic
ld (hl),#3E ;; End-of-stack mark for basic
RETURN dec hl ;; (for detect RETURN without GOSUB)
ld sp,hl
ld hl,#1303 ;; Standart error handler
push hl ;; (for displaying error messages)
ld (errsp),sp
jp runbas ;; 7030? Continue in 48 basic interpreter