Major
chip technologies roadmap
Nowadays, we have
various speeds of memories, for example 133MHz, 266MHz, 333MHz. Let's take
a look on the overview of the evolution of memory.
| Year Introduction |
Technology |
Speed Limit |
| 1987 |
FPM (Fast
Page Mode) |
50ns |
| 1995 |
EDO (Extended
Data Out) |
50ns |
| 1997 |
PC66 SDRAM |
66MHz |
| 1998 |
PC100 SDRAM |
100MHz |
| 1999 |
RDRAM |
800MHz |
| 1999/2000 |
PC133 SDRAM |
133MHz |
| 2000 |
DDR SDRAM
-I |
266MHz |
| 2001 |
DDR SDRAM
-I |
333MHz/400MHz |
| 2003 |
DDR SDRAM
-II |
400MHz? or
533MHz? |
FPM: Fast page
mode. A specialized method of DRAM operation that improves DRAM performance
over page mode operation under certain operation conditions. FPM enabled faster
access to data located within the same row.
EDO: Extended data
output. A variation of fast page mode and is faster than conventional DRAM.
It can begin retrieving the next block of memory at the same time that it
sends the previous block to the CPU. Conventional DRAM can only handle one
block of data at a time.
SDRAM: Synchronous
dynamic random access memory. Operates at a faster rate than both FPM and
EDO DRAM. It has a clock input that synchronizes all operations.
RDRAM: Rambus dynamic
random access memory. A high-speed memory interface that improves the performance
of conventional DRAM, but requires a larger die size and more manufacturing
steps.
DDR SDRAM: Double-data-rate
synchronous DRAM. A type of SDRAM that transfers data on both the rising and
falling edge of the clock signal, which effectively doubles the memory chip's
data throughput.