From Learn @ Cemetech
The current PC value plus three is pushed onto the stack. The MSB is loaded with $00 and the LSB is loaded with imm8.
RST $00 RST $08 ;rOP1ToOP2 RST $10 ;rFindSym RST $18 ;rPushRealO1 RST $20 ;rMove9ToOP1 RST $28 ;rBCALL RST $30 ;rFPAdd RST $38
All flags unaffected.
RST $28 is used by TI calculators for ROM calls.
#define bcall(label) rst $28 \ .dw label