In the days before DDR, notebooks typically used 144-pin SDRAM. Sporting modules by PQI, this 512 MB module operated at 3.3V and used a clock frequency of 133 MHz (PC133). PC133 was the last SDRAM standard ever approved by JEDEC. Computers that could run PC133 were also backward compatible with PC66 and PC100 modules. The maximum bandwidth for PC133 was 1066 MB/s.